Multicolor OLED arrays for high aperture displays

Abstract

A microcavity pixel design and fabrication method for an organic light emitting diode (OLED) array with a high aperture ratio suitable for light field displays. This is achieved by laterally overlapping intermediate electrodes and optical filler layers and reducing the lateral spacing. The OLED layers in the design have a uniform white OLED stack, allowing each layer to be deposited across the entire OLED array, simplifying fabrication. The optical path length in the optical microcavity of each subpixel is optimized by the thickness of the optical filler layer, allowing the white OLED stack to be uniform, reducing fabrication complexity.

Description

[Technical field]

[0001] (CROSS REFERENCE TO RELATED APPLICATIONS) This application claims priority to U.S. Patent Application No. 17 / 378,300, filed July 16, 2021, which is incorporated by reference herein in its entirety.

[0002] The present disclosure relates to patterning designs and fabrication methods for organic light emitting diode (OLED) devices with high aperture ratios suitable for light field displays. [Background technology]

[0003] Light field displays provide multiple fields of view, allowing the user to receive separate views with each eye. Current displays in this category provide interesting viewing experiences, but an attractive light field display requires very high pixel density, very low angular separation between views, and a large viewing angle. It is desirable for the user to experience a smooth transition between viewing zones while maintaining an independent perceptible view from adjacent views. A fundamental requirement in achieving these viewing parameters is to control the output characteristics of the radiation source. Organic light emitting diodes (OLEDs) coupled within a microcavity allow control of the spectral bandwidth and output angle of the resulting light.

[0004] One way to control the light output characteristics is through the use of microcavities. A microcavity is formed between two mirrors or reflective surfaces and can be a layered stack of non-absorbing materials, which can be, for example, a metal anode, a metal cathode, or a distributed Bragg reflector (DBR). The mirrors generally serve to reflect a range of wavelengths of light while maintaining the physical properties of the incident light. Two main design variables that affect the output characteristics of a microcavity are the reflectivities of the top and bottom surfaces (i.e., the opposing mirrors) and the optical path length Λ. The wavelength of light output by such an OLED structure depends in part on the optical path length of the microcavity. The optical path length can be manipulated by adjusting the thickness and / or number of layers that make up the microcavity.

[0005] When producing OLEDs of suitable size for light field displays, challenges arise when depositing the organic layers separately to achieve the thickness required for the desired optical path length for each color. One challenge for producing OLEDs suitable for light field displays is to achieve a high aperture ratio with pixels smaller than 10 μm using available manufacturing capabilities. The aperture ratio of a pixel is the ratio of the emitting area of ​​the pixel to the total area of ​​the display. A high aperture ratio can be achieved by maximizing the emitting area of ​​each pixel on the display. This reduces gaps in the viewing area and improves the image quality of light field displays. Achieving a high aperture ratio is particularly difficult when producing high resolution displays with small pixel sizes.

[0006] Wong et al., US Patent Publication No. 2021 / 0057670, describes an array of light-emitting OLED pixels. The disclosed pixels use multiple transparent or substantially transparent dielectric layers over each anode. The thickness of the dielectric layers is designed to optimize the emission of light of the desired color for that pixel. A white OLED layer is formed in a single deposition step in the OLED array, and the lateral spacing between each anode results in a reduced aperture ratio.

[0007] Park et al., U.S. Patent No. 10,790,473, describes an OLED device designed to achieve a high aperture ratio. A high aperture ratio is achieved by first connecting the reflective electrode of the anode and the transparent electrode at the corners of the subpixel area. Each subpixel has a microcavity structure, minimizing the pixel-defining layer between the subpixels. The spacing between the subpixels is not favorable for light field displays because the light-emitting area of ​​the display is not maximized.

[0008] A high aperture ratio is preferred for near-eye displays, such as virtual reality (VR) displays, augmented reality (AR) displays, microdisplays, and light field displays. There remains a need for micron-sized OLED pixel array designs and fabrication methods that achieve high aperture ratios at high display resolutions suitable for light field displays.

[0009] This background information is provided for the purpose of making known information believed by the applicant to be of possible relevance to the present invention. It is not necessarily intended, nor should it be construed, that any of the preceding information constitutes prior art against the present invention. [Prior art documents] [Patent documents]

[0010] [Patent Document 1] US Patent Application Publication No. 2021 / 0057670 [Patent Document 2] U.S. Patent No. 10,790,473 Summary of the Invention

[0011] The objective of the present disclosure is to provide an optical microcavity pixel device comprising an organic light emitting diode (OLED) and a photolithographic patterning method to achieve micron-sized pixels that obtain an aperture ratio of more than 70% when patterned in an array. Another objective of the present disclosure is to provide a method of OLED array patterning that can produce a light field display with a resolution of more than 1,000 ppi (pixels per inch). The optical microcavity pixel array comprises a distributed Bragg reflector (DBR) on a substrate and two or more subpixels comprising a semi-transparent or fully transparent electrode and a series of semi-transparent or fully transparent optical filler layers. Another objective of the present disclosure is to provide an optical microcavity pixel design structure in which the semi-transparent or fully transparent electrodes disposed on the DBR have a lateral overlap to reduce the lateral spacing, thereby increasing the aperture ratio of the light field display. The limitation, reduction, or elimination of the lateral spacing between colored electrodes can be accomplished using a layered series of semi-transparent or fully transparent filler layers interposed between overlapping electrodes of the first and second colors, the second and third colors, the first and third colors, or any combination thereof. The thickness of the filler layers is designed to tune the optical cavity of each pixel, thereby dictating the color produced by the optical microcavity pixel device. Another object of the present disclosure is to provide a method that reduces the complexity of the manufacturing process of high aperture OLED arrays.

[0012] In one aspect, an organic light emitting diode device is provided that includes a substrate, a distributed Bragg reflector (DBR) on the substrate, a first color electrode on the DBR that defines a first color microcavity, the first color electrode being connected to the substrate through a first via, a first optical filler layer on the DBR adjacent to the first color electrode, a second optical filler layer on the first optical filler layer that partially overlaps the first color electrode in an overlapping region, a second color electrode on the second optical filler layer that defines a second color microcavity, the second color electrode being connected to the substrate through a second via, a white organic light emitting diode (OLED) stack on the first color electrode and the second color electrode, and a top electrode on the white OLED stack.

[0013] In one embodiment, the electrodes of the second color partially overlap the electrodes of the first color.

[0014] In another embodiment, the first color microcavity has a first color optical path length between the DBR and the top electrode through the first color electrode, and the second color microcavity has a second color optical path length between the DBR and the top electrode through the second color electrode.

[0015] In another embodiment, the optical path length of the first color and the optical path length of the second first color are adjusted to provide desired first and second color pixels, respectively.

[0016] In other embodiments, the first optical filler layer and the second optical filler layer comprise a transparent polymer.

[0017] In other embodiments, the first optical filler layer and the second optical filler layer comprise a transparent inorganic dielectric material.

[0018] In another embodiment, the device further comprises a pixel defining layer that insulates the first color electrode from the second color electrode.

[0019] In other embodiments, the pixel defining layer comprises one or more of an inorganic insulating dielectric and an organic material.

[0020] In another embodiment, the substrate is a thin film transistor (TFT) substrate.

[0021] In another embodiment, the device further comprises a second DBR on the top electrode.

[0022] In other embodiments, the top electrode is the cathode and the bottom electrode is the anode.

[0023] In other embodiments, the top electrode is the anode and the bottom electrode is the cathode.

[0024] In another embodiment, the device further comprises a third optical filler layer on the first optical filler layer defining a third color microcavity over the second color electrode and below the white OLED stack, a fourth optical filler layer on the third optical filler layer and overlapping the second color electrode, and a third color electrode on the fourth optical filler layer overlapping the second color electrode and connected to the substrate through a third via.

[0025] In another aspect, a method for manufacturing a multicolor microcavity organic light emitting diode (OLED) array is provided, the method including depositing a distributed Bragg reflector (DBR) on a substrate; depositing a first color electrode on the DBR that defines a first color microcavity, the first color electrode being connected to the substrate through a first via; depositing a first optical filler layer on the DBR adjacent to the first color electrode; depositing a second optical filler layer on the first optical filler layer that partially overlaps the first color electrode at an overlap region; depositing a second color electrode on the second optical filler layer that defines a second color microcavity, the second color electrode being connected to the substrate through a second via; depositing a white organic light emitting diode (OLED) stack on the first color electrode and the second color electrode; and depositing a top electrode on the white OLED stack.

[0026] In one embodiment of the method, a white OLED stack is deposited over the entire OLED array.

[0027] In other embodiments of the method, the white OLED stack is deposited using thermal evaporation, spin casting, or inkjet printing.

[0028] In another embodiment of the method, the top electrode is deposited using thermal evaporation or sputtering.

[0029] In another embodiment, the method further comprises depositing a pixel defining layer that insulates the first color electrode from the second color electrode.

[0030] In other embodiments of the method, the pixel defining layer is deposited using sputtering, spin coating, thermal evaporation, chemical vapor deposition, atomic layer deposition, or spin casting.

[0031] In another embodiment, the method further comprises depositing a second DBR on the top electrode.

[0032] In another embodiment of the method, the first color electrode, the second color electrode, and the top electrode are deposited using sputtering, thermal evaporation, or spin coating.

[0033] In other embodiments of the method, the first optical filler layer and the second optical filler layer are deposited using sputtering, thermal evaporation, chemical vapor deposition, or atomic layer deposition.

[0034] In other embodiments of the method, the DBR is deposited using sputtering, thermal evaporation, chemical vapor deposition, or atomic layer deposition.

[0035] In another embodiment, the method further includes, prior to depositing the white OLED stack, depositing a third optical filler layer selected for a third color on the first optical filler layer, where the third optical filler layer overlaps the electrode of the first color; depositing a fourth optical filler layer selected for a third color on the third optical filler layer, where the fourth optical filler layer overlaps the electrode of the second color; and depositing a series of electrodes of the third color on the fourth optical filler layer. [Brief description of the drawings]

[0036] These and other features of the present invention will become more apparent in the following detailed description, when taken in conjunction with the accompanying drawings.

[0037] [Figure 1A] 1 illustrates one embodiment of a cross-sectional view of a two-color optical microcavity organic light-emitting diode (OLED) array according to the present disclosure.

[0038] [Figure 1B] FIG. 1B shows a close-up view of the one-color optical microcavity OLED device depicted in FIG. 1A.

[0039] [Figure 1C] 1B shows a close-up view of the two-color optical microcavity OLED device depicted in FIG. 1A.

[0040] [Diagram 2] 1 illustrates another embodiment of a two-color optical microcavity OLED array according to the present disclosure including a pixel-defining layer (PDL).

[0041] [Figure 3A] 1 illustrates another embodiment of a two-color optical microcavity OLED array according to the present disclosure that includes an additional DBR deposited on the cathode.

[0042] [Figure 3B] 3B shows a close-up view of the two-color optical microcavity OLED device depicted in FIG. 3A.

[0043] [Figure 4] 1 illustrates one embodiment of a cross-section of a three-color optical microcavity OLED array according to the present disclosure.

[0044] [Diagram 5] 1 illustrates another embodiment of a three-color optical microcavity OLED array according to the present disclosure including a PDL.

[0045] [Figure 6] 1 illustrates another embodiment of a three-color optical microcavity OLED array according to the present disclosure that includes an additional DBR deposited on the cathode.

[0046] [Figure 7] 1 illustrates one embodiment of the optical path from a TFT substrate to the emission of a two-color optical microcavity OLED array according to the present disclosure.

[0047] [Figure 8] 1 illustrates one embodiment of the optical path from a TFT substrate to the emission of a three-color optical microcavity OLED array according to the present disclosure.

[0048] [Figure 9] FIG. 1 illustrates a top view of one embodiment of light emission from a three-color optical microcavity OLED array according to the present disclosure.

[0049] [Figure 10A] FIG. 1 shows step 1 of the proposed two-color OLED array patterning process for depositing the DBR.

[0050] [Figure 10B] 13 shows step 2 of the proposed two-color OLED array patterning process to form vias for the first color electrodes through the DBR.

[0051] [Figure 10C]FIG. 1 shows step 3 of the proposed two-color OLED array patterning process for depositing the first color electrode.

[0052] [Figure 10D] FIG. 2 shows step 4 of the proposed two-color OLED array patterning process for depositing photoresist.

[0053] [Figure 10E] 13 shows step 5 of the proposed two-color OLED array patterning process for a photolithography step in which the photoresist is partially removed by etching by partially exposing the embodiment to UV light.

[0054] [Figure 10F] 13 shows step 6 of the proposed two-color OLED array patterning process for depositing the first optical filler layer.

[0055] [Figure 10G] FIG. 13 shows step 7 of the proposed two-color OLED array patterning process for the photolithography step of removing the first optical filler layer deposited on the photoresist by lifting off the remaining photoresist.

[0056] [Figure 10H] FIG. 13 shows a top view of step 7 of the proposed two-color OLED array patterning process.

[0057] [Figure 10I] 13 shows step 8 of the proposed two-color OLED array patterning process for depositing the second optical filler layer.

[0058] [Figure 10J] 13 shows step 9 of the proposed two-color OLED array patterning process to form vias for a second color electrode through the DBR, the first optical filler layer, and the second optical filler layer.

[0059] [Figure 10K] 1 shows step 10 of the proposed two-color OLED array patterning process for depositing the second color electrode.

[0060] [Figure 10L] FIG. 1 shows a top view of step 10 of the proposed two-color OLED array patterning process.

[0061] [Figure 10M] 1 shows step 11 of the proposed two-color OLED array patterning process for depositing a white OLED stack.

[0062] [Figure 10N] 1 shows step 12 of the proposed two-color OLED array patterning process for depositing a cathode as the top reflective surface to form the optical microcavities of the OLED array.

[0063] [Figure 11A] FIG. 1 shows step 1 of the proposed three-color OLED array patterning process for depositing the DBR.

[0064] [Figure 11B] FIG. 13 shows step 2 of the proposed three-color OLED array patterning process to form vias for the first color electrodes through the DBR.

[0065] [Figure 11C] FIG. 1 shows step 3 of the proposed three-color OLED array patterning process for depositing the first color electrode.

[0066] [Figure 11D] FIG. 2 shows step 4 of the proposed three-color OLED array patterning process for depositing photoresist.

[0067] [Figure 11E]13 shows step 5 of the proposed three-color OLED array patterning process for a photolithography step in which the photoresist is partially removed by etching by partially exposing the embodiment to UV light.

[0068] [Figure 11F] 13 shows step 6 of the proposed three-color OLED array patterning process for depositing the first optical filler layer.

[0069] [Figure 11G] FIG. 13 shows step 7 of the proposed three-color OLED array patterning process for the photolithography step of removing the first optical filler layer deposited on the photoresist by lifting off the remaining photoresist.

[0070] [Figure 11H] FIG. 13 shows a top view of step 7 of the proposed three-color OLED array patterning process.

[0071] [Figure 11I] 13 shows step 8 of the proposed three-color OLED array patterning process for depositing the second optical filler layer.

[0072] [Figure 11J] 13 shows step 9 of the proposed three-color OLED array patterning process to form vias for a second color electrode through the DBR, the first optical filler layer, and the second optical filler layer.

[0073] [Figure 11K] 1 shows step 10 of the proposed three-color OLED array patterning process for depositing the second color electrode.

[0074] [Figure 11L] FIG. 1 shows a top view of step 10 of the proposed three-color OLED array patterning process.

[0075] [Figure 11M] 1 shows step 11 of the proposed three-color OLED array patterning process for depositing photoresist.

[0076] [Figure 11N] 12 shows step 12 of the proposed three-color OLED array patterning process for a photolithography step in which the photoresist is partially removed by etching by partially exposing the embodiment to UV light.

[0077] [Figure 11O] 13 shows step 13 of the proposed three-color OLED array patterning process for depositing the third optical filler layer.

[0078] [Figure 11P] 14 shows step 14 of the proposed three-color OLED array patterning process for the photolithography step of removing the third optical filler layer deposited on the photoresist by lifting off the remaining photoresist.

[0079] [Figure 11Q] 1 shows step 15 of the proposed three-color OLED array patterning process for depositing the fourth optical filler layer.

[0080] [Figure 11R] Shown is step 16 of the proposed three-color OLED array patterning process for forming vias for a third color electrode through the DBR, the first optical filler layer, the third optical filler layer, and the fourth optical filler layer.

[0081] [Figure 11S] 1 shows step 17 of the proposed three-color OLED array patterning process for depositing the third color electrode.

[0082] [Figure 11T]FIG. 14 shows a top view of step 17 of the proposed three-color OLED array patterning process.

[0083] [Figure 11U] 1 shows step 18 of the proposed three-color OLED array patterning process for depositing a white OLED stack.

[0084] [Figure 11V] 1 shows step 19 of the proposed three-color OLED array patterning process for depositing a cathode as the top reflective surface to form the optical microcavity of the OLED device. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0085] definition Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs.

[0086] The use of the words "a" or "an" when used herein in conjunction with the term "comprising" may mean "one," but is also consistent with the meaning of "one or more," "at least one," and "one or more."

[0087] As used herein, the terms "comprising," "having," "including," and "containing," and grammatical variations thereof, are inclusive or open ended and do not exclude additional, unrecited elements and / or method steps. The term "consisting essentially of," when used herein in connection with a composition, device, article, system, use, or method, indicates that additional elements and / or method steps may be present, but that these additions do not substantially affect the manner in which the recited composition, device, article, system, method, or use functions. A composition, device, article, system, use, or method described herein as comprising certain elements and / or steps may, in certain embodiments, essentially comprise those elements and / or steps, whether or not those embodiments are specifically mentioned, and may comprise those elements and / or steps in other embodiments.

[0088] As used herein, the term "about" refers to about a + / - 10% variation from a given value. It should be understood that such a variation is always included in any given value provided herein, whether or not it is specifically referred to.

[0089] The recitation of ranges herein is intended to convey both the range and the individual values ​​falling within the range, unless otherwise indicated herein, values ​​in the same place as the numbers used to denote the range.

[0090] The use of any example or exemplary language, such as "such as," "exemplary embodiment," "illustrative embodiment," and "for example," is intended to illustrate or illustrate aspects, embodiments, variations, elements, or features related to the invention and is not intended to limit the scope of the invention.

[0091] As used herein, the terms "connect" and "connected" refer to any direct or indirect physical association between elements or features of the present disclosure. These terms may be understood to refer to elements or features that are partially or completely contained, attached, coupled, positioned, joined together, in communication, operably associated, etc., with one another, even if there are other elements or features between the elements or features described as being connected.

[0092] As used herein, the term "OLED" refers to an organic light-emitting diode, an optoelectronic device that emits light under the application of an external voltage. An OLED has a light-emitting electroluminescent layer or organic material or species that emits light in response to an electric current. OLEDs can be divided into two main classes: those made of organic small molecules and those made of organic polymers. Without being bound by theory, when an electric current is applied, the anode injects holes and the cathode injects electrons into the organic layer. The injected holes and electrons each migrate toward the oppositely charged electrode. When an electron and hole localize on the same molecule, an exciton is formed, which is a localized electron-hole pair that has an excited energy state. Light is emitted when the exciton relaxes via a light-emitting mechanism. Types of OLEDs include, but are not limited to, active matrix OLEDs (AMOLEDs) and passive matrix OLEDs (PMOLEDs). AMOLEDs have a total layer of cathodes, organic molecules, and anodes. The anode layer has thin film transistor (TFT) faces parallel to it to form a matrix. This helps to switch each pixel to its on or off state as desired, thus forming an image. Thus, the pixel can be turned off whenever it is not needed or there is a black image on the display, reducing the energy required to illuminate the display. It is the least power-consuming type of OLED and has a faster refresh rate suitable for video. PMOLED has a similar composition to AMOLED, but the cathode lines are placed at right angles to the anode lines. Electrical control is achieved through the anode and cathode lines, activating the pixels at the intersections to generate light. The display background of PMOLED is always black, and the color displayed when the pixel is turned on is a predetermined color. PMOLED pixels are fixed to a single color and are not suitable for dynamic images or displays. OLEDs can be top-emitting or bottom-emitting. Top-emitting OLEDs have a substrate that is either opaque or reflective. If the emitted light passes through a transparent or semi-transparent bottom electrode and substrate, the OLED is bottom-emitting.Top-emitting OLEDs are generally more suitable for active-matrix applications because they can be more easily integrated with non-transparent transistor backplanes.

[0093] As used herein, the term "DBR" refers to a distributed Bragg reflector, which is an optical mirror composed of different dielectric layers having different refractive indices in an alternating order.

[0094] As used herein, the term "optical path length", denoted by Λ, refers to the distance between two points (P1, P2) that describes the refractive index (n) of the material through which light passes. In an exemplary OLED device, the medium through which the light passes may include one or more semi-transparent or transparent intermediate electrodes and other layers, as well as layers including a white OLED stack. The optical path length is defined as a function of:

number

[0095] As used herein, the term "light field" refers to a function that describes the amount of light flowing in all directions through a point in space. A light field can represent radiance as a function of the position and direction of light in free space, preferably without occlusions. Light fields can be generated synthetically, for example, by various rendering processes, or captured from a light field camera or an array of light field cameras.

[0096] As used herein, the term "light field display" is a device that reconstructs a light field. In one example, the light field can be reconstructed from a finite number of light field radiance samples input to a light field display device. The radiance samples generally represent red, green, and blue (RGB) color components. For reconstruction in a light field display, the light field can also be understood as a mapping from a four-dimensional space to a single RGB color, where the fourth dimension includes the vertical and horizontal dimensions of the display and two dimensions that describe the directional component of the light field. In one example, the light field can be defined as a function: LF: (x,y,u,v) → (r,g,b) Given x f ,y f In the case of LF(x f ,y f , u,v) represent two-dimensional (2D) images called "element images", and an element image is a given x f ,y f This is a directional image of the light field from a position. A series of elemental images is called an "integral image". An integral image can be understood as the entire light field required for a light field display.

[0097] As used herein, the term "aperture ratio," in describing an optical display, refers to the ratio of the light-emitting area compared to the total pixel area, defined as a function.

number

[0098] As used herein, the term "pixel" refers to the light source and light emitting mechanism used to create the display.

[0099] As used herein, the term "subpixel" refers to a structure consisting of a light-emitting device contained within an optical microcavity.

[0100] As used herein, the term "electrode" refers to a conductor through which electricity passes to or from an object, substance, or area.

[0101] As used herein, the term "cathode" refers to a negatively charged electrode through which electrons enter an electrical device.

[0102] As used herein, the term "anode" refers to a positively charged electrode through which electrons leave an electrical device.

[0103] As used herein, the term "patterning" refers to the technique of transferring a pattern onto a target material.

[0104] As used herein, the term "wavelength" is a measure of the distance between two identical peaks (high points) or troughs (low points) of a wave, which is a repeating pattern of moving energy such as light or sound.

[0105] Described herein are microcavity organic light emitting diode (OLED) designs and methods for preparing micron-sized, multicolor optical microcavity OLED arrays. Light field displays require pixel densities of at least 25,000 pixels per inch (ppi), with each pixel being less than 20 μm. Most preferably, light field displays with high display resolution have pixel densities of greater than 5,000 ppi. Achieving high aperture ratios at these resolutions can be achieved by maximizing the emitting area of ​​each subpixel and minimizing the subpixel spacing. The present disclosure provides optical microcavity pixel devices with organic light emitting diodes (OLEDs), and photolithographic patterning methods for achieving micron-sized pixels that, when patterned into arrays, yield aperture ratios of greater than 70%, suitable for light field displays with resolutions of greater than 1,000 ppi. This can be achieved by patterning transparent or semi-transparent optical filler layers and intermediate electrodes to laterally overlap other intermediate electrodes in the OLED array to reduce lateral spacing and increase the aperture ratio of the resulting OLED array. This lateral overlap design allows the designer to optimize the optical properties of each OLED device and the aperture ratio of the OLED array as a whole. While the industry definition of high aperture ratio for displays with micron-sized pixels is 70%, this design allows the display to achieve an aperture ratio of nearly or about 100%, creating a high quality display suitable for light field displays and other applications. Also disclosed are methods for designing and fabricating arrays of OLED devices that emit light including, but not limited to, yellow, red, green, or blue light.

[0106] Various features of the present invention will become apparent from the following detailed description, taken in conjunction with the illustrative drawings. The design parameters, design methods, configurations, and uses of the optical microcavity OLED design process and structure disclosed herein are described with reference to various examples that represent embodiments that are not intended to limit the scope of the invention described and claimed herein. Those skilled in the art to which the present invention pertains may understand that there may be other variations, examples, and embodiments of the present invention not disclosed herein that can be implemented in accordance with the teachings of the present disclosure without departing from the scope of the present disclosure.

[0107] Each OLED in the device comprises an electrode configured to interface with the substrate, an optical microcavity including a distributed Bragg reflector (DBR), and a cathode. The optical microcavity is operatively associated with or connected to one or more reflective surfaces to substantially collimate, manipulate, or condition light. At least one of the reflective surfaces is a light-propagating reflective surface connected to the optical microcavity to propagate light out of the optical microcavity. The present disclosure provides individually addressable red, green, and blue (RGB) subpixels. The subpixel sizes currently described range from nanoscale to a few microns. The DBR is constructed from alternating stacks of dielectric materials of specific thicknesses, as described herein, to ensure that the optical path length is one-quarter of the design wavelength, making it suitable for use in OLEDs of any color. The highest reflectivity of the DBR is achieved when the layer thicknesses are selected such that the optical path length of each layer is one-quarter of the resonant wavelength. Each layer is λ Bragg With an optical path length of λ / 4, all reflections add in phase and the transmission decreases exponentially as a function of the mirror thickness. At wavelengths longer or shorter than the stopband, the reflections start to get out of phase and so the total reflection decreases. This results in a broadband region of high reflectivity centered on the Bragg wavelength, called the stopband, with oscillating side lobes on either side. DBRs are generally constructed from a pair of two different dielectric layers with different refractive indices, but with an optical path length of λ for each layer. Bragg / 4. It may also be made up of multiple dielectric materials or other transparent materials with a contrast of n. A multi-layer mirror comprises alternating layers of substantially non-absorbing material of appropriately selected thicknesses. Typically, each layer has a thickness

number

[0108] FIG. 1A shows one embodiment of a cross-section of a two-color optical microcavity OLED array described herein, having two OLED devices of a first color and one OLED device of a second color. The illustrated OLED array comprises a DBR 12 deposited on a substrate 10. In this embodiment, the substrate 10 is a TFT substrate, which is a device that forms the base structure of one embodiment of an OLED and provides electrical control to switch each pixel or subpixel to its on or off state as required. The TFT comprises several layers, including a metal gate electrode, a gate insulator, a semiconductor layer, and source / drain electrodes deposited on the substrate. The TFT substrate also preferably has a planarization layer on which the OLED material is deposited. The DBR 12 comprises a series of alternating high-index dielectric layers 76 and low-index dielectric layers 78. The number of high-index dielectric layers 76 and low-index dielectric layers 78 can be any integer number. In the illustrated embodiment, the DBR 12 can serve as the first reflective surface of the optical microcavity of each OLED device in the OLED array.

[0109] Before each electrode in the series of electrodes for an array of first color OLED devices, referred to herein as first color electrodes 14A, 14B, is deposited on the DBR 12, each via of the first color OLED, referred to herein as first color vias 16A, 16B, is dry etched through the DBR 12. This provides electrical connection from the substrate 10 to the first color electrodes 14A, 14B. The first color vias 16A, 16B may be etched using an etching technique, such as reactive ion etching, anodic plasma etching, magnetically enhanced reactive ion etching, triode reactive ion etching, or transmission coupled plasma etching. In the present embodiment, a preferred dry etching method such as reactive ion etching is used. After the first color vias 16A, 16B are etched through the DBR 12, the first color electrodes 14A, 14B are deposited on the DBR 12 using a shadow mask. The first optical filler layer 18 is patterned directly on the DBR 12 between the first color electrodes 14A, 14B using photolithography for each second color OLED device in the OLED array. The patterning can be, for example, by chemically engraving the transferred pattern into the transferred material or by depositing new material onto the transferred material using a series of post-processing processes. A second optical filler layer 20 is then patterned for each second color OLED device in the OLED array on the first optical filler layer 18 overlying the first optical filler layer 18 through a shadow mask or using photolithography. The second optical filler layer 20 may overlap the first color electrodes 14A, 14B to form overlap regions 80A, 80B. The overlap regions 80A, 80B provide a tolerance that mitigates registration errors in manufacturing, thus increasing the aperture ratio of the display by reducing the lateral spacing between the OLED devices on the substrate 10. The optical filler layer is designed to be transparent to visible light and electrically insulating, and acts as an electrical insulating layer to prevent crosstalk between the first color electrodes 14A, 14B and the second color electrodes 22 in the overlap regions 80A, 80B.

[0110] Before the second color electrodes 22 are deposited on the second optical filler layer 20, a second color via 24 for each of the second color electrodes 22 is dry etched using reactive ion etching through the second optical filler layer 20, the first optical filler layer 18, and the DBR 12. The second color via 24 provides an electrical connection from the substrate 10 to the second color electrodes 22. The second color electrodes 22 are then patterned on the second optical filler layer 20 using a shadow mask, and preferably the width of the second color electrodes 22 is the same as the width of the second optical filler layer 20. For a two-color OLED array, a layer of a white OLED stack 26 is then deposited over the entire OLED array. For a three-color OLED array, a third optical filler layer, a fourth optical filler layer, a third color via, and a third color electrode are deposited for the third color, followed by the deposition of the white OLED stack 26. The uniformly deposited OLED stack emits white light, and for each color optical microcavity, the optical path length is adjusted to achieve a particular color. A cathode 28 is then deposited onto the white OLED stack 26, for example using thermal evaporation. In this embodiment, the cathode 28 is a reflective material deposited at a thickness that results in a transmission greater than 0% and is used to form the optical microcavities of each OLED device.

[0111] In this embodiment, the substrate 10 comprises a non-conductive component that forms the base of the OLED device, and a conductive component that provides power to each electrode. An example can be a thin film transistor (TFT) substrate that is composed of one or more semiconductor materials, a gate insulator, and a substrate. Semiconductor materials can include organic materials such as hydrogenated amorphous silicon, polycrystalline silicon, amorphous oxide semiconductors, cadmium selenide, zinc oxide, pentacene, poly(3-hexylthiophene), poly(3-alkylthiophene), and poly(3-octylthiophene), or transparent electrodes such as indium zinc oxide (IZO) or indium tin oxide (ITO). Indium tin oxide (ITO) is typically encountered as an oxygen-saturated composition with a formulation of 74% In, 18% O2, and 8% Sn by weight. ITO is also commonly used as an anode material in OLED structures due to its suitable electrical conductivity, nearly transparent and colorless optical properties, and the ability to be deposited by established methods. ITO can also be used to construct the anode layer of an OLED device according to the present disclosure. The gate insulator can be a metal passivation material with a transparent insulator such as SiO2 and Si3N4, or an organic material such as polymethylmethacrylate. The substrate can be a non-conductive material such as glass. The DBR 12 comprises alternating high and low refractive index dielectric layers 76 and 78, which can be composed of TiO2 and SiO2. The first color electrodes 14A, 14B and the second color electrodes 22 can be semi-transparent or transparent conductive materials such as ITO, conductive polymers such as doped polyaniline, or thin layers (between 5 and 35 nm, preferably less than 10 nm) of metals or alloys, or carbon-based materials such as graphene. Transparent conductive materials such as ITO are preferred due to their high transmittance values ​​(80-85%) and low reflectance and absorbance.

[0112] The first optical filler layer 18 and the second optical filler layer 20 may be transparent polymers, such as polyimide, or inorganic transparent dielectrics with various refractive index values, such as Al2O3, SiO2, or Si3N4. The first optical filler layer 18 and the second optical filler layer 20 may be composed of the same material or different materials. The optical filler layers 18, 20 may be deposited, for example, by sputtering, thermal evaporation, chemical vapor deposition, or atomic layer deposition. One preferred method of deposition is sputtering, which allows the designer to precisely adjust the thickness of the layers during deposition. The thickness of the optical filler layers and the materials that comprise them are designed to adjust the optical path length of each particular color. A preferred material for the optical filler layers has a similar refractive index as the bottom electrode. For example, ITO may be used for the second color electrode 22, and Al2O3 may be used for both the first optical filler layer 18 and the second optical filler layer 20. The white OLED stack 26 includes thin film layers of organic materials, which typically include one or more of an organic hole injection layer (HIL), an organic hole transport layer (HTL), an emissive layer (EML), an organic electron transport layer (ETL), and an organic electron injection layer. The sequence of layers in the white OLED stack is designed to emit white light. The individual color of each OLED device is achieved by adjusting the optical path length of each optical microcavity. Each layer of the white OLED stack 26 can be deposited by thermal evaporation, spin casting, or inkjet printing. In this embodiment, one preferred method for depositing the white OLED stack 26 is thermal evaporation. The cathode 28 can be a reflective metal with a reflectivity greater than 90%, such as aluminum, cadmium, or silver. This embodiment shows a conventional OLED configuration, where the first color electrodes 14A, 14B and the second color electrode 22 under the white OLED stack 26 are anodes, and the top electrode above the white OLED stack 26 is the cathode 28. The microcavity OLEDs described herein have substantially reflective top and bottom surfaces with substantially transparent intermediate layers that collectively create a resonance within the optical microcavity to produce the optical path length required for the desired color.In this configuration, where the DBR 12 is the bottom reflective surface and the cathode 28 is the top reflective surface, the cathode 28 is slightly less reflective than the DBR 12, allowing light generated within the optical microcavities to be emitted through the top of the OLED array. In another configuration, the OLED array may be configured as an array of inverted OLED devices, where the bottom electrode deposited below the white OLED stack 26 is a completely transparent cathode, and the top electrode above the white OLED stack is a reflective anode. The OLED arrays described herein may also be configured to be arrays of bottom-emitting OLED devices, where the bottom electrode, DBR 12, and substrate 10 are slightly less reflective than the top electrode, and emit light through the substrate 10. The OLED arrays may also be configured to be composed of any combination of inverted or non-inverted and top- or bottom-emitting OLEDs.

[0113] In an optical microcavity, the optical path length of each color is equal to the peak wavelength of the color divided by 2 and multiplied by a positive integer. therefore,

number

[0114] Each element that comprises the optical microcavity has an optical path length that is determined by the refractive index of the material and its thickness. The total optical path length of each color can be determined by the optical path length of each element that comprises the optical microcavity, namely, DBR 12, electrodes 14, 22, optical filler layers 18, 20, white OLED stack 26, and cathode 28. In addition to the refractive index and thickness, the penetration depth into DBR 12 and cathode 28 is considered because DBR 12 and cathode 28 are reflective surfaces that form the boundaries of the optical microcavity. In this embodiment, DBR 12 and cathode 28 are uniform, and white OLED stack 26 is designed to emit white light for the entire OLED array. The optical path length of each color includes the penetration depth of DBR 12 and the penetration depth of cathode 28. These penetration depths are built into the design considerations and are constant throughout the OLED array. Although DBR 12 and cathode 28 are present, they are not used to adjust the optical path length to emit a particular color. therefore,

number

[0115] The optical path length Λ of each first color OLED device in the OLED array C1 (herein referred to as the optical path length of the first color 30A, 30B) is the optical path length of the first electrode (herein referred to as the optical path length of the first electrode (Λ e1 ) 34A, 34B) and the white OLED stack (Λ OLED ) 32. The optical path length Λ of each second color OLED device in the OLED array C2 (Herein, the optical path length of the second color (Λ C2 ) 36) is the optical path length (Λ) of the first optical filler layer. f1 ) 38, the optical path length of the second optical filler layer (Λ f2 ) 40, the optical path length of the second color electrode (Λ e2 ) 42, and the optical path length (Λ OLED) 32. Because the optical path length of each element in the optical microcavity is determined by the thickness of the element and its refractive index, by adjusting the thickness of a particular element in the optical microcavity, a designer can optimize the optical path length for a desired color. Once the white OLED stack 26 is deposited over the OLED array, the white OLED stack (Λ OLED The optical path length of the first color (Λ C1 ) 30A, 30B, which can be achieved by optimizing the thickness of the white OLED stack 26. In particular, the optical path length of the first color (Λ C1 ) should be approximately equal to the peak wavelength of the first color divided by two integers. Since the optical path length of the white OLED stack 32 is uniform across the OLED array, the second optical filler layer (Λ f2 ) 40 is the optical path length of the second color (Λ C2 3A, 3B, and the thickness of the second optical filler layer 20 may be designed to produce the required optical path length for the white OLED stack 32. Because the white OLED stack 32 can be uniform, it is advantageous to use the optical path length of the white OLED stack 26 to optimize the optical path length for the first colors 30A, 30B, and the optical path length of the second optical filler layer 40 to optimize the optical path length for the second color 36. A uniform white OLED stack 26 can then be deposited over the entire OLED array, thereby simplifying manufacturing.

[0116] FIG. 1B shows an expanded view of the monochromatic optical microcavity OLED device depicted in FIG. 1A. The OLED device comprises a DBR 12 deposited on a substrate 10, which may be a TFT substrate. The DBR 12 comprises a series of alternating high and low index dielectric layers 76 and 78. It should be noted that although the number of pairs of high and low index dielectric layers 76 and 78 shown in FIG. 1B is three with six layers, the DBR can be composed of any integer number of layers. This configuration allows the DBR 12 to function as the first reflective surface of the optical microcavity of each OLED device in the OLED array. A first color electrode 14 is deposited on the DBR 12 using a shadow mask. The layers comprising the white OLED stack 26 are then deposited individually across the OLED array. Each layer of the white OLED stack 26 can be deposited, for example, by thermal evaporation, spin casting, and inkjet printing, preferably by thermal evaporation. In this embodiment, the white OLED stack 26 can comprise one or more of the following layers: an organic hole injection layer (HIL) 84, an organic hole transport layer (HTL) 86, an emissive layer (EML) 88, an organic electron transport layer (ETL) 90, and an organic electron injection layer (EIL) 92. In some configurations, the white OLED stack 26 can comprise a single EML 88, where emissive molecules of a particular color are combined in the EML 88 to produce white light. In alternative configurations, the white OLED stack 26 can comprise multiple EMLs 88, which can be referred to as tandem or stacked white OLEDs. In a tandem white OLED, white light is produced from all the emissive EMLs 88 in the white OLED stack 26. In a tandem OLED configuration, additional charge generation layers can be deposited to act as additional injection layers and artificial metal electrodes. The combination of organic layers in the white OLED stack 26 is designed to emit white light, and each optical microcavity adjusts the optical path length of the various elements to achieve a particular color. Cathode 28 is then deposited, for example using thermal evaporation, on the white OLED stack 26. In this embodiment, cathode 28 is a reflective material and is used to form the optical microcavity for each OLED device.

[0117] FIG. 1C shows an expanded view of the two-color optical microcavity OLED device described in FIG. 1A. The OLED device comprises a DBR 12 deposited on a substrate 10. In this embodiment, the substrate 10 is a TFT substrate. The DBR 12 comprises a series of alternating high index dielectric layers 76 and low index dielectric layers 78. The number of high index dielectric layers 76 and low index dielectric layers 78 can be any integer. This configuration allows the DBR 12 to function as the first reflective surface of the optical microcavity of each OLED device in the OLED array. A first color electrode 14 is deposited on the DBR 12 using a shadow mask. A first optical filler layer 18 is patterned directly on the DBR 12 adjacent to the first color electrode 14 using photolithography for each second color OLED device in the OLED array. A second optical filler layer 20 is then patterned for each second color OLED device in the OLED array on the first optical filler layer 18 through a shadow mask or using photolithography, and the second optical filler layer 20 can cover the entire first optical filler layer 18 and overlap the first color electrode 14 to form an overlap region 80. The overlap region 80 mitigates alignment errors in manufacturing, and thus increases the aperture ratio of the display by reducing the lateral spacing between the OLED devices on the substrate 10. A second color electrode 22 is patterned on the second optical filler layer 20 using a shadow mask, and preferably the width of the second color electrode 22 is the same width as the second optical filler layer 20. Although only first and second microcavities are shown here, it is understood that the OLED array comprises a plurality of first color microcavities with a first electrode and a plurality of second color microcavities with a second electrode. It is further understood that an OLED array also typically comprises a plurality of three different color microcavities to provide red, green, and blue emission.

[0118] The layers comprising the white OLED stack 26 are then deposited individually across the OLED array. Each layer of the white OLED stack 26 can be deposited by thermal evaporation, spin casting, or inkjet printing. In this embodiment, the preferred method is thermal evaporation. In this embodiment, the organic layers comprising the white OLED stack 26 are deposited on the first and second color electrodes 14, 22 in the following order: organic hole injection layer (HIL) 84, organic hole transport layer (HTL) 86, light emitting layer (EML) 88, organic electron transport layer (ETL) 90, and organic electron injection layer (EIL) 92. The white OLED stack 26 can further comprise one or more of each organic layer. The organic layers of the white OLED stack 26 are designed together to emit white light, and each optical microcavity adjusts the optical path length of the various elements to achieve a particular color. The cathode 28 is then deposited on the white OLED stack 26 using, for example, thermal evaporation. In this embodiment, cathode 28 is a reflective material and is used to form an optical microcavity for each OLED device.

[0119] FIG. 2 shows an alternative embodiment of a two-color optical microcavity OLED array according to the present disclosure, including a pixel-defining layer (PDL) 44. The cross section shows two OLED devices of a first color and one OLED device of a second color. The OLED array comprises a DBR 12 deposited on a substrate 10. In this embodiment, the substrate 10 is a TFT substrate and is the device that forms the base structure of this embodiment. The DBR 12 comprises a series of alternating high-index dielectric layers 76 and low-index dielectric layers 78. Before the first-color electrodes 14A, 14B are deposited on the DBR 12, first-color vias 16A, 16B are dry etched through the DBR 12 to provide electrical connections from the substrate 10 to the first-color electrodes 14A, 14B. In this embodiment, the preferred dry etching method is reactive ion etching. The first-color electrodes 14A, 14B are then patterned on the DBR 12 using a shadow mask. The first optical filler layer 18 is patterned using photolithography on the DBR 12 between the first color electrodes 14A, 14B. The second optical filler layer 20 can be deposited on the first optical filler layer 18, completely covering the first optical filler layer 18 and overlapping the first color electrodes 14A, 14B to form overlap regions 80A, 80B. The second optical filler layer can be patterned using a shadow mask or photolithography. The overlap regions 80A, 80B provide a tolerance that mitigates registration errors in manufacturing, thus increasing the aperture ratio of the display by reducing the lateral spacing between OLED devices on the substrate 10.

[0120] Before the second color electrode 22 is deposited, a second color via 24 is dry etched using reactive ion etching through the optical filler layer 20, 18 and DBR 12 to provide an electrical connection to the substrate 10. The second color electrode 22 is patterned on the second optical filler layer 20 using a shadow mask, with the width of the second color electrode 22 equal to the width of the second optical filler layer 20. In this embodiment, an optional PDL 44 is patterned using a shadow mask to cover areas of the second color electrode 22 and second optical filler layer 20 that overhang the adjacent first color electrodes 14A, 14B. The PDL 44 prevents electrical shorts between the first color electrodes 14A, 14B and the second color electrodes 22, reducing crosstalk across the OLED array. Crosstalk generally refers to light leaking from one pixel to another when emitted, which can interfere with image quality causing loss of contrast, loss of depth resolution, viewer discomfort, and duplication of the displayed image. The PDL 44 can be deposited, for example, by sputtering, spin coating, thermal evaporation, chemical vapor deposition, atomic layer deposition, spin casting, etc. The optional PDL 44 can be composed of an insulating dielectric, for example, an inorganic material such as Al2O3, Si3N4, or SiO2, or an organic material such as a photosensitive polyimide. In a three-color OLED device, the PDL layer can also connect the third color electrode to the second color electrode. The layers comprising the white OLED stack 26 are deposited over the entire OLED array. The cathode 28 is then deposited on the white OLED stack 26 by thermal evaporation. In this embodiment, the cathode 28 is a reflective material and is therefore used to form an optical microcavity for each OLED device.

[0121] The first color (Λ C1 The optical path length of the first electrode (Λ) 30A, 30B is e1 ) 34A, 34B and the optical path length of the white OLED stack (Λ OLED ) 32. The second color (Λ C2 The optical path length of the first optical filler layer (Λ f1 ) 38 optical path length, second optical filler layer (Λf2 ) 40 optical path length, second color electrode (Λ e2 ) 42 optical path length, and the white OLED stack (Λ OLED ) 32. Because the optical path length of each element in the optical microcavity is determined by the thickness of the element and its refractive index, by adjusting the thickness of a particular element in the optical microcavity, a designer can tune the optical path length of a desired color. Once the white OLED stack 26 is deposited across the OLED array, the white OLED stack (Λ OLED The optical path length of the first color (Λ C1 ) 30A, 30B can be designed to adjust the optical path length, which can be achieved by optimizing the thickness of the white OLED stack 26. Since the optical path length of the white OLED stack 32 is uniform across the OLED array, the second optical filler layer (Λ f2 ) 40 is the optical path length of the second color (Λ C2 ) 36 may be designed across the thickness of the second optical filler layer 20 to produce the required optical path length.

[0122] Using the optical path length of the white OLED stack 32 to optimize the optical path length of the first colors 30A, 30B, and using the optical path length of the second optical filler layer 40 to optimize the optical path length of the second color 36 is advantageous because it allows the white OLED stack 26 to be uniform. A uniform white OLED stack 26 can then be deposited across the entire OLED array, thereby simplifying manufacturing.

[0123] FIG. 3A shows another embodiment of a two-color optical microcavity OLED array with a second DBR 12B deposited on top of the cathode 28. The cross section shows two OLED devices of a first color and one OLED device of a second color. The OLED array comprises a first DBR 12A deposited on a substrate 10. In this embodiment, the substrate 10 is a TFT substrate and is the device that forms the base structure of this embodiment. The first DBR 12A is a series of alternating high index dielectric layers 76 and low index dielectric layers 78. Before the first color electrodes 14A, 14B are deposited on the first DBR 12A, first color vias 16A, 16B are dry etched through the first DBR 12A to provide electrical connection from the substrate 10 to the first color electrodes 14A, 14B. In a preferred embodiment, the vias are formed using reactive ion etching. The first color electrodes 14A, 14B are then patterned on the first DBR 12A using a shadow mask. The first optical filler layer 18 is then patterned on the first DBR 12A between the first color electrodes 14A, 14B using photolithography. The second optical filler layer 20 is then deposited to completely cover the first optical filler layer 18 and preferably overlap the first color electrodes 14A, 14B, forming overlap regions 80A, 80B. The second optical filler layer 20 can be patterned using a shadow mask or using photolithography. The overlap regions 80A, 80B provide a tolerance that mitigates registration errors in manufacturing, thus increasing the aperture ratio of the display by reducing the lateral spacing between the OLED devices on the substrate 10.

[0124] Before the second color electrode 22 is deposited, a second color via 24 is dry etched using reactive ion etching through the optical filler layer 20, 18 and the first DBR 12A to provide an electrical connection to the substrate 10. The second color electrode 22 is patterned on the second optical filler layer 20 using a shadow mask, with the width of the second color electrode 22 approximately equal to the width of the second optical filler layer 20. The layers comprising the white OLED stack 26 are then deposited over the entire OLED array. The cathode 28 is then deposited on the white OLED stack 26 by thermal evaporation. In this embodiment, a further DBR 12B is deposited on top of the cathode 28. The second DBR 12B has a series of alternating high and low index dielectric layers 76 and 78. The cathode 28 is made of a semi-transparent or transparent material, and the DBR 12B is used to form the optical microcavities for each OLED device.

[0125] Each element that comprises the optical microcavity has an optical path length determined by the refractive index of the material and its thickness. The total optical path length of each color can be determined by the optical path length of each element that comprises the optical microcavity, namely, the first DBR 12A, the first electrodes 14A, 14B, the second electrodes 22, the optical filler layers 18, 20, the white OLED stack 26, the cathode 28, and the second DBR 12B. Since the first DBR 12A and the second DBR 12B are reflective surfaces that form the boundaries of the optical microcavity, in addition to the refractive index and thickness, the penetration depth into the DBRs 12A, 12B is considered. In this embodiment, the DBRs 12A, 12B and the cathode 28 are uniform, and the white OLED stack 26 is designed to emit white light for the entire OLED array. The optical path length of each color includes the penetration depth of the first DBR 12A, the penetration depth of the second DBR 12B, and the optical path length of the cathode 28. These penetration depths and corresponding optical path lengths are built into the design considerations and are constant across the OLED array: first DBR 12A, second DBR 12B, and cathode 28 are not used to tune the optical path length to emit a particular color. therefore,

number

[0126] The first color (Λ C1 The optical path length of the first electrode (Λ) 30A, 30B is e1 ) 34A, 34B and the optical path length of the white OLED stack (Λ OLED ) 32. The second color (Λ C2 The optical path length of the first optical filler layer (Λ f1 ) 38 optical path length, second optical filler layer (Λ f2 ) 40 optical path length, second color electrode (Λ e2 ) 42 optical path length, and the white OLED stack (Λ OLED ) 32. Because the optical path length of each element in the optical microcavity is determined by the thickness of the element and its refractive index, by adjusting the thickness of a particular element in the optical microcavity, a designer can tune the optical path length of a desired color. Once the white OLED stack 26 is deposited over the OLED array, the white OLED stack (Λ OLED The optical path length of the first color (Λ C1 ) 30A, 30B can be designed to adjust the optical path length, which can be achieved by optimizing the thickness of the white OLED stack 26. Since the optical path length of the white OLED stack 32 is uniform across the OLED array, the second optical filler layer (Λ f2 ) 40 is the optical path length of the second color (Λ C2 3. The white OLED stack 26 may also be designed across the thickness of the second optical filler layer 20 to generate the required optical path length for the white OLED stack 32, 30B, and the second optical filler layer 40 may be used to optimize the optical path length for the second color 36. Using the optical path length of the white OLED stack 32 to optimize the optical path length for the first color 30A, 30B and the optical path length of the second optical filler layer 40 to optimize the optical path length for the second color 36 is advantageous because the white OLED stack 26 may be uniform across the OLED optical microcavity array. A uniform white OLED stack 26 may also be deposited across the entire OLED array, simplifying manufacturing.

[0127] FIG. 3B shows an expanded view of the two-color optical microcavity OLED device shown in FIG. 3A. The OLED device comprises a first DBR 12A deposited on a substrate 10, preferably a TFT substrate. The first DBR 12A is composed of alternating high index dielectric layers 76 and low index dielectric layers 78. The number of layers of high index dielectric layers 76 and low index dielectric layers 78 can be any integer number of layers, with three pairs shown in this configuration comprising six layers. In this embodiment, the first DBR 12A serves as the first reflective surface of the optical microcavity of each OLED device in the OLED array. A first color electrode 14 is deposited on the first DBR 12A using a shadow mask. A first optical filler layer 18 is patterned using photolithography for each second color OLED device in the OLED array directly on the first DBR 12A, adjacent to the first color electrode 14. The second optical filler layer 20 can then be patterned by shadow mask or photolithography for each second color OLED device in the OLED array on the first optical filler layer 18 to cover the entire first optical filler layer 18 and overlap the first color electrode 14 to form an overlap region 80. The overlap region 80 mitigates alignment errors in manufacturing and thus increases the aperture ratio of the display by reducing the lateral spacing between the OLED devices on the substrate 10. The second color electrode 22 is patterned on the second optical filler layer 20 using a shadow mask, and preferably the width of the second color electrode 22 is the same as the width of the second optical filler layer 20.

[0128] The layers comprising the white OLED stack 26 are then deposited individually across the OLED array. Each layer of the white OLED stack 26 can be deposited, for example, by thermal evaporation, spin casting, or inkjet printing. In this embodiment, the preferred method is thermal evaporation. The organic layers comprising the white OLED stack 26 are then deposited on the first and second color electrodes 14, 22 in the following order: organic hole injection layer (HIL) 84, organic hole transport layer (HTL) 86, light emitting layer (EML) 88, organic electron transport layer (ETL) 90, and organic electron injection layer (EIL) 92. The white OLED stack 26 can comprise one or more of each organic layer. The organic layers are designed to emit white light, and each optical microcavity adjusts the optical path length of the various elements to achieve a particular color. The cathode 28 is then deposited on the white OLED stack 26 using, for example, thermal evaporation. In this embodiment, the cathode 28 is composed of a semi-transparent or transparent material, and the second DBR 12B is deposited on the cathode 28. The second DBR 12B comprises a series of alternating high index dielectric layers 76 and low index dielectric layers 78. The number of high index dielectric layers 76 and low index dielectric layers 78 in the second DBR 12B can also be any integer number. This configuration allows the second DBR 12B to act as the top reflective surface for the optical microcavities of each OLED device in the OLED array.

[0129] FIG. 4 shows one embodiment of a cross-section of a three-color optical microcavity OLED array according to the present disclosure. The OLED array comprises a DBR 12 deposited on a substrate 10. The cross-section shows two OLED devices of a first color and a single OLED device for each of a second and third color. In this embodiment, the substrate 10 is a TFT substrate, a device that forms the base structure of the OLED array. The DBR 12 comprises a series of alternating high index dielectric layers 76 and low index dielectric layers 78, the number of which can be any integer number. In this configuration, the DBR 12 is the first reflective surface for the optical microcavity of each OLED device in the OLED array.

[0130] Before the first color electrodes 14A, 14B for an array of first color OLED devices are deposited on the DBR 12, first color vias 16A, 16B are dry etched through the DBR 12 to provide electrical connections from the substrate 10 to the first color electrodes 14A, 14B. The vias can be etched, for example, by reactive ion etching, anodic plasma etching, magnetically enhanced reactive ion etching, triode reactive ion etching, and transparent coupled plasma etching. One preferred dry etching method for constructing the vias is reactive ion etching. After the first color vias 16A, 16B are etched through the DBR 12, the first color electrodes 14A, 14B are patterned on the DBR 12 using a shadow mask. Then, for each second color OLED device in the OLED array, a first optical filler layer 18 is patterned using photolithography directly on the DBR 12 between the first color electrodes 14A, 14B. A second optical filler layer 20 may then be deposited on the first optical filler layer 18, partially covering and overlapping the first color electrode 14A to form overlap region 80A. The second optical filler layer 20 may be patterned using a shadow mask or photolithography. The overlap region 80A provides a tolerance that mitigates registration errors in manufacturing, thus increasing the aperture ratio of the display by reducing the lateral spacing between OLED devices on the substrate 10.

[0131] Before the second color electrode 22 is deposited on the second optical filler layer 20, the second color via 24 is dry etched using reactive ion etching through the second optical filler layer 20, the first optical filler layer 18, and the DBR 12. The second color via 24 provides an electrical connection from the substrate 10 to the second color electrode 22. The second color electrode 22 is then patterned using a shadow mask on the second optical filler layer 20, and preferably the width of the second color electrode 22 is the same as the width of the second optical filler layer 20. The third optical filler layer 58 can then be patterned using photolithography for each third color OLED device in the OLED array on the first optical filler layer 18 adjacent to the second optical filler layer 20 to overlap the first color electrode 14B to form an overlap region 80C. A fourth optical filler layer 60 may be deposited for each third color OLED device in the OLED array on the third optical filler layer 58 and overlap the second color electrode 22 to form overlap regions 80D. The fourth optical filler layer 60 may be patterned using a shadow mask or photolithography. The overlap regions 80C, 80D may mitigate registration errors in manufacturing and increase the aperture ratio of the display by reducing the lateral spacing between the OLED devices on the substrate 10.

[0132] Before the third color electrode 62 is deposited on the fourth optical filler layer 60, the third color via 64 is dry etched, preferably using reactive ion etching, through the fourth optical filler layer 60, the third optical filler layer 58, the first optical filler layer 18, and the DBR 12. The third color via 64 provides an electrical connection from the substrate 10 to the third color electrode 62. The third color electrode 62 is then patterned on the fourth optical filler layer 60 using a shadow mask, preferably with the width of the third color electrode 62 being the same as the width of the fourth optical filler layer 60. The layers comprising the white OLED stack 26 are then deposited over the entire OLED array. The cathode 28 is then deposited on the white OLED stack 26, for example using thermal evaporation. In this embodiment, the cathode 28 is a reflective material and is therefore used to form an optical microcavity for each OLED device.

[0133] In this embodiment, the substrate 10 may be a thin film transistor (TFT) substrate consisting of a semiconductor material, a gate insulator, and a substrate. The semiconductor material may include, for example, hydrogenated amorphous silicon, polycrystalline silicon, amorphous oxide semiconductor, cadmium selenide, zinc oxide; organic materials such as pentacene, poly(3-hexylthiophene), poly(3-alkylthiophene), poly(3-octylthiophene); or a transparent electrode such as ITO. The gate insulator may be a transparent insulator such as SiO2 and Si3N4, or a metal passivated with an organic material such as polymethylmethacrylate. The substrate may be a non-conductive material such as glass. The DBR 12 comprises alternating high refractive index dielectric layers 76 and low refractive index dielectric material layers 78. The electrodes 14A, 14B, 22, 62 can be semi-transparent or transparent conductive materials such as ITO, conductive polymers such as doped polyaniline, or thin layers of metals or alloys (between 5 and 35 nm, preferably less than 10 nm), and carbon-based materials such as graphene. Transparent conductive materials such as ITO are preferred for the present disclosure due to their high transmittance (80-85%) and low reflectance and absorbance. The optical filler layers 18, 20, 58, 60 can comprise transparent polymers such as polyimide, or inorganic transparent dielectrics with various refractive index values ​​such as Al2O3, SiO2, or Si3N4. The optical filler layers 18, 20, 58, 60 can be deposited by sputtering, thermal evaporation, chemical vapor deposition, atomic layer deposition. A preferred material for the optical filler layers has a similar refractive index to the bottom electrode, for example, ITO is a preferred material for the second color electrode 22 and the third color electrode 62, in which case Al2O3 is a preferred material for the optical filler layers. The preferred deposition method is sputtering, which allows the designer to precisely control the thickness of the layers during deposition. The white OLED stack 26 includes thin film layers of organic materials, which typically include one or more of an organic hole injection layer (HIL), an organic hole transport layer (HTL), an emissive layer (EML), an organic electron transport layer (ETL), and an organic electron injection layer. The series of OLED layers is designed to emit white light.Each layer of the white OLED stack 26 can be deposited by thermal evaporation, spin casting, and inkjet printing. In this embodiment, the preferred method is thermal evaporation. The individual color of each OLED device is achieved by modulating the optical path length of each optical microcavity. The cathode 28 can be a reflective metal with a reflectivity of over 90%, such as aluminum, cadmium, or silver. This embodiment shows a conventional OLED configuration in which the bottom electrode 14A, 14B, 22, 62 below the white OLED stack 26 is the anode, and the electrode above the white OLED stack 26 is the cathode 28. The present disclosure may also be configured as an array of inverted OLED devices, where the bottom electrode deposited before the white OLED stack 26 is the cathode 28, and the top electrode above the white OLED stack 26 is the anode. The present disclosure may also be configured as an array of bottom-emitting OLED devices, where the bottom electrode, DBR 12, and substrate 10 are semi-transparent or transparent, and emit light through the substrate 10. The disclosed embodiments can be configured to be any combination of inverted or non-inverted and top or bottom emitting.

[0134] Each element that comprises the optical microcavity has an optical path length that is determined by the refractive index of the material and its thickness. The total optical path length of each color can be determined by the optical path length of each element that comprises the optical microcavity, namely, DBR 12, electrodes 14, 22, 62, optical filler layers 18, 20, 58, 60, white OLED stack 26, and cathode 28. In addition to the refractive index and thickness, the penetration depth into DBR 12 and cathode 28 is considered because DBR 12 and cathode 28 are reflective surfaces that form the boundaries of the optical microcavity. In this embodiment, DBR 12 and cathode 28 are uniform, and white OLED stack 26 is designed to emit white light for the entire OLED array. The optical path length of each color includes the penetration depth of DBR 12 and the penetration depth of cathode 28. These penetration depths are incorporated into the design considerations, but are constant throughout the OLED array. The DBR 12 and cathode 28 shown are not used to tailor the optical path length to emit a particular color. therefore,

number

[0135] The optical path length Λ of each first color OLED device in the OLED array C1 (herein referred to as the optical path length of the first color 30A, 30B) is the optical path length of the first electrode (herein referred to as the optical path length of the first electrode (Λ e1 ) 34A, 34B) and the white OLED stack (Λ OLED ) 32. The optical path length Λ of each second color OLED device in the OLED array C2 (Herein, the optical path length of the second color (Λ C2 ) 36) is the optical path length (Λ) of the first optical filler layer. f1 ) 38, the optical path length of the second optical filler layer (Λ f2 ) 40, the optical path length of the second color electrode (Λ e2 ) 42, and the optical path length (Λ OLED ) 32. The optical path length Λ of each third color OLED device in the OLED array C3 (Herein, the optical path length of the third color (Λ C3 ) 66) is a first optical filler layer (Λ f1 ) 38 optical path length, the third optical filler layer (Λ f3 ) 68 optical path length, the fourth optical filler layer (Λ f4 ) 70 optical path length, the third color electrode (Λ e3 ) 72 optical path length, and the white OLED stack (Λ OLED ) is determined by the sum of the 32 optical path lengths.

[0136] Since the optical path length of each element in the optical microcavity is determined by the thickness of the element and its refractive index, by adjusting the thickness of a particular element in the optical microcavity, a designer can optimize the optical path length for a desired color. Once the white OLED stack 26 is deposited over the OLED array, the white OLED stack (Λ OLED The optical path length of the first color (Λ C1) 30A, 30B, which can be achieved by optimizing the thickness of the white OLED stack 26. In particular, C1 The optical path length of the white OLED stack 32 should be approximately equal to or equal to the peak wavelength of the first color divided by two integer numbers. Since the optical path length of the white OLED stack 32 is uniform across the OLED array, the second optical filler layer (Λ f2 ) 40 is the optical path length of the second color (Λ C2 The thickness of the second optical filler layer 20 can also be designed to adjust the optical path length required for the fourth optical filler layer (Λ f4 ) 70 is the optical path length of the third color (Λ C3 ) 66. Using the optical path length of the white OLED stack 32 to optimize the optical path length of the first colors 30A, 30B, and the optical path length of the optical filler layers 40, 70 to optimize the optical path length of the second color 36 and the optical path length of the third color 66 is advantageous because the white OLED stack 26 can be made uniform. A uniform white OLED stack 26 can then be deposited across the entire OLED array, thereby simplifying manufacturing.

[0137] FIG. 5 shows another embodiment of a three-color optical microcavity OLED array according to the present disclosure, including a pixel-defining layer (PDL) 44. The cross section shows two OLED devices of a first color and a single OLED device each of a second color and a third color. The OLED array comprises a DBR 12 deposited on a substrate 10. In this embodiment, the substrate 10 is a TFT substrate and is a device that forms the base structure of this embodiment. The DBR 12 comprises a series of alternating high-index dielectric layers 76 and low-index dielectric layers 78. Before the first color electrodes 14A, 14B are deposited, first color vias 16A, 16B are dry etched through the DBR 12 for each first color electrode 14A, 14B to provide electrical connection to the substrate 10. In this embodiment, the preferred dry etching method is reactive ion etching. The first color electrodes 14A, 14B are patterned on the DBR 12 using a shadow mask. The first optical filler layer 18 is patterned using photolithography on the DBR 12 between the first color electrodes 14A, 14B. The second optical filler layer 20 may be deposited on the first optical filler layer 18, partially covering it and overlapping the first color electrode 14A to form an overlap region 80A. The second optical filler layer 20 may be patterned using a shadow mask or photolithography. The overlap region 80A provides a tolerance that mitigates registration errors in manufacturing, thus increasing the aperture ratio of the display by reducing the lateral spacing between the OLED devices on the substrate 10. Second color vias 24 are then dry etched using reactive ion etching through the optical filler layers 18, 20 and the DBR 12 to provide electrical connection of the second color electrode 22 to the substrate 10. The second color electrode 22 is patterned on the second optical filler layer 20 using a shadow mask, and the width of the second color electrode 22 is equal to the width of the second optical filler layer 20. The third optical filler layer 58 can be patterned on the first optical filler layer 18 adjacent to the second optical filler layer 20 using photolithography, and overlap the first color electrode 14B to form an overlap region 80C.The fourth optical filler layer 60 may be deposited on the third optical filler layer 58 and overlap the second color electrode 22 to form an overlap region 80D. The fourth optical filler layer 60 may be patterned by shadow mask or photolithography. The overlap regions 80C, 80D may mitigate alignment errors in manufacturing and thus increase the aperture ratio of the display by reducing the lateral spacing between the OLED devices on the substrate 10. A third color via 64 is then dry etched using reactive ion etching through the optical filler layers 58, 60 and the DBR 12 to provide electrical connection to the substrate 10. A third color electrode 62 is patterned on the fourth optical filler layer 60 using a shadow mask, with the width of the third color electrode 62 being equal to the width of the fourth optical filler layer 60. In this embodiment, an optional PDL 44 is patterned using a shadow mask to cover the areas of the second and third color electrodes 22, 62 and the optical filler layers 20, 60, 58 that overhang the respective adjacent first color electrodes 14A, 14B and second color electrodes 22. The PDL 44 is then deposited between the first color electrodes 14A and 22, the second color electrodes 22 and the third color electrodes 62, and the third color electrodes 62 and the first color electrodes 14B. The PDL 44 can reduce crosstalk across the OLED array and prevent electrical shorts. The layers comprising the white OLED stack 26 are then deposited over the entire OLED array. The cathode 28 is then deposited on the white OLED stack 26 using, for example, thermal evaporation. In this embodiment, the cathode 28 is a reflective material and forms part of the optical microcavity of each OLED device.

[0138] Each element that comprises the optical microcavity has an optical path length that is determined by the refractive index of the material and its thickness. The total optical path length of each color can be determined by the optical path length of each element that comprises the optical microcavity, namely, DBR 12, electrodes 14, 22, 62, optical filler layers 18, 20, 58, 60, white OLED stack 26, and cathode 28. In addition to the refractive index and thickness, the penetration depth into DBR 12 and cathode 28 is considered because DBR 12 and cathode 28 are reflective surfaces that form the boundaries of the optical microcavity. In this embodiment, DBR 12 and cathode 28 are uniform, and white OLED stack 26 is designed to emit white light for the entire OLED array. The optical path length of each color includes the penetration depth of DBR 12 and the penetration depth of cathode 28. These penetration depths are incorporated into the design considerations, but are constant throughout the OLED array. The DBR 12 and cathode 28 are not used to adjust the optical path length to emit a particular color. therefore,

number

[0139] The first color (Λ C1 The optical path length of the first electrode (Λ) 30A, 30B is e1 ) 34A, 34B and the optical path length of the white OLED stack (Λ OLED ) 32 and the optical path length of the second color (Λ C2 The optical path length of the first optical filler layer (Λ f1 ) 38 optical path length, second optical filler layer (Λ f2 ) 40 optical path length, second color electrode (Λ e2 ) 42 optical path length, and the white OLED stack (Λ OLED ) 32 optical path lengths. The third color (Λ C3 The optical path length of the first optical filler layer (Λ f1 ) 38 optical path length, the third optical filler layer (Λ f3 ) 68 optical path length, the fourth optical filler layer (Λ f4 ) 70 optical path length, the third color electrode (Λ e3) 72 optical path length, and the white OLED stack (Λ OLED ) is determined by the sum of the 32 optical path lengths.

[0140] Because the optical path length of each element in the optical microcavity is determined by the thickness of the element and its refractive index, by adjusting the thickness of a particular element in the optical microcavity, a designer can optimize the optical path length for a desired color. Once the white OLED stack 26 is deposited across the OLED array, the white OLED stack (Λ OLED The optical path length of the first color (Λ C1 ) 30A, 30B can be designed to adjust the optical path length, which can be achieved by optimizing the thickness of the white OLED stack 26. Since the optical path length of the white OLED stack 32 is uniform across the OLED array, the second optical filler layer (Λ f2 ) 40 is the optical path length of the second color (Λ C2 ) 36. Similarly, the thickness of the fourth optical filler layer (Λ f4 The optical path length of the third color (Λ) 70 is designed across the thickness of the fourth optical filler layer 60 to provide a C3 ) 66 can be adjusted to the required optical path length.

[0141] Using the optical path length of the white OLED stack 32 to optimize the optical path length of the first colors 30A, 30B, and using the optical path length of the optical filler layers 40, 70 to optimize the optical path length of the second and third colors 36, 66, is advantageous because it allows the white OLED stack 26 to be uniform. A uniform white OLED stack 26 can then be deposited across the entire OLED array, thereby simplifying manufacturing.

[0142] FIG. 6 shows another embodiment of a three-color optical microcavity OLED array according to the present disclosure, including a second DBR 12B deposited on the cathode 28. The cross section shows two OLED devices of a first color and a single OLED device each of a second color and a third color. The OLED array comprises a first DBR 12A deposited on a substrate 10. In this embodiment, the substrate 10 is a TFT substrate that forms the base structure of the embodiment. The first DBR 12A comprises a series of alternating high index dielectric layers 76 and low index dielectric layers 78. First color vias 16A, 16B are dry etched through the first DBR 12A for each first color electrode 14A, 14B, providing electrical connection to the substrate 10. A shadow mask is then used to pattern the first color electrodes 14A, 14B on the first DBR 12A. A first optical filler layer 18 is then patterned using photolithography on the first DBR 12A between the first color electrodes 14A, 14B. A second optical filler layer 20 can then be deposited on the first optical filler layer 18, partially covering it and overlapping the first color electrode 14A to form an overlap region 80A. A shadow mask or photolithography can then be used to pattern the second optical filler layer 20. The overlap region 80A provides a tolerance that mitigates registration errors in manufacturing, thus increasing the aperture ratio of the display by reducing the lateral spacing between the OLED devices on the substrate 10. A second color via 24 is then etched through the first and second optical filler layers 18 and 20 and the first DBR 12A to provide electrical connection of the second color electrode 22 to the substrate 10. A second color electrode 22 is then patterned using a shadow mask onto the second optical filler layer 20, with the width of the second color electrode 22 equal to the width of the second optical filler layer 20. A third optical filler layer 58 can then be patterned using photolithography onto the first optical filler layer 18 adjacent to the second optical filler layer 20, overlapping the first color electrode 14B to form an overlap region 80C.A fourth optical filler layer 60 can then be deposited on the third optical filler layer 58 and overlap the second color electrode 22 to form an overlap region 80D. The fourth optical filler layer 60 can be patterned using a shadow mask or photolithography. The overlap regions 80C, 80D can mitigate alignment errors in manufacturing and thus increase the aperture ratio of the display by reducing the lateral spacing between the OLED devices on the substrate 10. A third color via 64 is then dry etched through the optical filler layers 58, 60 and the first DBR 12A to provide an electrical connection to the substrate 10. A third color electrode 62 is then patterned on the fourth optical filler layer 60 using a shadow mask, with the width of the third color electrode 62 being equal to the width of the fourth optical filler layer 60. The layers comprising the white OLED stack 26 are deposited over the entire OLED array. Cathode 28 is then deposited on the white OLED stack 26 using, for example, thermal evaporation. In this embodiment, a second DBR 12B is deposited on cathode 28. The second DBR 12B comprises a series of alternating high index dielectric layers 76 and low index dielectric layers 78. Cathode 28 is composed of a semi-transparent or transparent material, and the second DBR 12B is used to form the optical microcavities for each OLED optical microcavity device.

[0143] Each element that comprises the optical microcavity has an optical path length determined by the refractive index of the material and its thickness. The total optical path length of each color can be determined by the optical path length of each element that comprises the optical microcavity, namely, the first DBR 12A, the electrodes 14, 22, 62, the optical filler layers 18, 20, 58, 60, the white OLED stack 26, the cathode 28, and the second DBR 12B. Since the first DBR 12A and the second DBR 12B are reflective surfaces that form the boundaries of the optical microcavity, the calculation of each optical path length takes into account the penetration depth into the DBRs 12A and 12B in addition to the refractive index and thickness. In this embodiment, the DBRs 12A, 12B and the cathode 28 are uniform, and the white OLED stack 26 is designed to emit white light for the entire OLED array. The optical path length of each color includes the penetration depth of the first DBR 12A, the penetration depth of the second DBR 12B, and the optical path length of the cathode 28. These penetration depths and corresponding optical path lengths are built into the design considerations and are constant across the OLED array: first DBR 12A, second DBR 12B, and cathode 28 are not used to tune the optical path length to emit a particular color. therefore,

number

[0144] The first color (Λ C1 The optical path length of the first electrode (Λ) 30A, 30B is e1 ) 34A, 34B and the optical path length of the white OLED stack (Λ OLED ) 32 and the optical path length of the second color (Λ C2 The optical path length of the first optical filler layer (Λ f1 ) 38 optical path length, second optical filler layer (Λ f2 ) 40 optical path length, second color electrode (Λ e2 ) 42 optical path length, and the white OLED stack (Λ OLED ) 32 optical path lengths. The third color (Λ C3 The optical path length of the first optical filler layer (Λ f1 ) 38 optical path length, the third optical filler layer (Λ f3) 68 optical path length, the fourth optical filler layer (Λ f4 ) 70 optical path length, the third color electrode (Λ e3 ) 72 optical path length, and the white OLED stack (Λ OLED ) is determined by the sum of the 32 optical path lengths.

[0145] Because the optical path length of each element in the optical microcavity is determined by the thickness of the element and its refractive index, by adjusting the thickness of a particular element in the optical microcavity, a designer can optimize the optical path length for a desired color. Once the white OLED stack 26 is deposited across the OLED array, the white OLED stack (Λ OLED The optical path length of the first color (Λ C1 ) 30A, 30B can be designed to adjust the optical path length, which can be achieved by optimizing the thickness of the white OLED stack 26. Since the optical path length of the white OLED stack 32 is uniform across the OLED array, the second optical filler layer (Λ f2 ) 40 is the optical path length of the second color (Λ C2 ) 36. Similarly, the thickness of the fourth optical filler layer (Λ f4 The optical path length of the third color (Λ) 70 is designed across the thickness of the fourth optical filler layer 60 to provide a C3 ) 66. Using the optical path length of the white OLED stack 32 to optimize the optical path length of the first colors 30A, 30B and the optical path length of the optical filler layers 40, 70 to optimize the optical path lengths of the second and third colors 36, 66 is advantageous because it allows the white OLED stack 26 to be uniform. A uniform white OLED stack 26 can then be deposited across the entire OLED array, thereby simplifying manufacturing.

[0146] 7 shows one embodiment of the light path from the substrate 10 to the first color emission 50A, 50B and second color emission 52 of a two-color optical microcavity OLED array according to the present disclosure. Each subpixel in the series of subpixels of the array of first color OLED devices, referred to herein as first color subpixels 46A, 46B, is the width of the light emitting area of ​​each first color OLED device, designated as first color emission 50A, 50B, respectively. Each subpixel in the series of subpixels of the array of second color OLED devices, referred to herein as second color subpixels 48, is the width of the light emitting area of ​​each second color OLED device, designated as second color emission 52. Current originating from the substrate 10 flows through the first color vias 16A, 16B and second color vias 24 to the first color electrodes 14A, 14B and second color electrode 22, respectively, through the white OLED stack 26 to the cathode 28. As will be appreciated by those skilled in the art, the many layers that comprise the white OLED stack 26 create emissive regions where electrons radiate energy in the form of photons of light that are emitted as first color emission 50A, 50B and second color emission 52, respectively. The regions under the first color emission 50A, 50B can be considered individual optical microcavities for the first color. The design of the optical microcavities is optimized to emit light of the first color. The regions under the second color emission 52 can be considered individual optical microcavities for the second color. The design of the optical microcavities is optimized to emit light of the second color. The optical microcavities form regions where optical resonance occurs to generate and emit light of a particular color. This light is optimized for the first and second colors through the design of the length of the corresponding optical microcavities created by the distance between the top of the DBR 12 and the bottom of the cathode 28. The white OLED stack 26 is also designed to create the desired optical microcavities for the first color OLED device. First optical filler layer 18 and second optical filler layer 20 are transparent or semi-transparent and create the desired optical microcavity length for the second color OLED device.The patterning of the first color electrodes 14A, 14B and the second color electrodes 22 is designed to minimize lateral spacing, allowing the first color subpixels 46A, 46B and second color subpixels 48 and their corresponding light-emitting areas 50A, 50B, 52, respectively, to fully utilize the light-emitting area, thereby increasing the aperture ratio of the light field display.

[0147] FIG. 8 illustrates one embodiment of the light paths from the substrate 10 to the first color emission 50A, 50B, second color emission 52, and third color emission 56 of a three color optical microcavity OLED array according to the present disclosure. Each subpixel in the series of subpixels of the array of first color OLED devices, referred to herein as first color subpixels 46A, 46B, is the width of the emissive area of ​​each first color OLED device, designated as first color emission 50A, 50B. Each subpixel in the series of subpixels of the array of second color OLED devices, referred to herein as second color subpixels 48, is the width of the emissive area of ​​each second color OLED device, designated as second color emission 52. Each subpixel in the series of subpixels of the array of third color OLED devices, referred to herein as third color subpixels 54, is the width of the emissive area of ​​each third color OLED device, designated as third color emission 56. It will be understood that a three-color OLED array according to the present disclosure comprises a plurality of first color subpixels, second color subpixels, and third color subpixels. Current generated in the substrate 10 flows through the vias 16A, 16B, 24, 64 to the electrodes 14A, 14B, 22, 62, and through the white OLED stack 26 to the cathode 28. The layers comprising the white OLED stack 26 form emissive regions where electrons radiate energy in the form of photons of light, which are emitted as first color emission 50A, 50B, second color emission 52, and third color emission 56. The emitted light is optimized for the first, second, and third colors through the length of the corresponding optical microcavities created by the distance between the top of the DBR 12 and the bottom of the cathode 28, and the white OLED stack 26 is designed to create the desired optical microcavities for the first color OLED device. The first optical filler layer 18 and the second optical filler layer 20 are transparent or semi-transparent to create the desired optical microcavity length for the second color OLED device. The first optical filler layer 18, the third optical filler layer 58, and the fourth optical filler layer 60 are transparent or semi-transparent to create the desired optical microcavity length for the third color OLED device.The patterning of the first color electrodes 14A, 14B, second color electrodes 22, and third color electrodes 62 minimizes lateral spacing to allow the first color subpixels 46A, 46B, second color subpixels 48, and third color subpixels 54 and their corresponding light-emitting areas 50A, 50B, 52, 56 to fully utilize the light-emitting area, thereby increasing the aperture ratio of the light field display.

[0148] FIG. 9 is a top view of light emission from a three-color optical microcavity OLED array with overlapping subpixels according to the present disclosure. The overlapping patterning of the first color electrode, the second color electrode, and the third color electrode minimizes lateral spacing and overlaps the three colors of the subpixels and their corresponding light-emitting areas. This allows the OLED array to fully utilize the light-emitting area, thereby increasing the aperture ratio of the light field display. As shown, the first color emission 50, the second color emission 52, and the third color emission 56 overlap. FIG. 9 shows a delta triplet subpixel configuration, which is one possible configuration of a three-color OLED array as currently described.

[0149] Fabrication of optical microcavity OLED devices suitable for light field displays is inherently complex due to the pixel size required to achieve a high aperture display. Figures 10A-10N show a method for fabricating a two-color OLED array according to the present disclosure.

[0150] FIG. 10A shows the first step in fabrication, where DBR 12 is deposited on substrate 10. In this embodiment, substrate 10 is a TFT substrate, which is the device that forms the base structure of this embodiment. It is understood that DBR 12, as shown in FIG. 10A, comprises alternating high and low index dielectric layers. Each layer of DBR 12 can be deposited by sputtering, thermal evaporation, chemical vapor deposition, and atomic layer deposition. The preferred deposition method for this embodiment is sputtering.

[0151] 10B shows first color vias 16A, 16B dry etched through the DBR 12 to connect to the substrate 10. The vias can be etched by reactive ion etching, anodic plasma etching, magnetically enhanced reactive ion etching, triode reactive ion etching, and transmission coupled plasma etching. In this embodiment, the preferred dry etching method is reactive ion etching.

[0152] FIG. 10C shows the first color electrodes 14A, 14B deposited on the DBR 12. The first color vias 16A, 16B provide electrical connection of the first color electrodes 14A, 14B to the substrate 10. The electrodes can be patterned by sputtering, thermal evaporation, and spin coating. In this embodiment, sputtering is the preferred deposition method. A shadow mask can be used to deposit elements, such as the first color electrodes 14A, 14B in this embodiment, in the desired pattern. A shadow mask is generally a microstructure or stencil used to precisely define device areas for various applications suitable for deposition, etching, or processing of the substrate. The shadow mask is designed with specific perforations that allow precise patterning of the elements during deposition when placed on the substrate. Precision is especially important when depositing micron-sized OLED devices, as alignment or deposition errors can occur. This results in suboptimal electrical and optical properties of the OLED device and reduces the aperture ratio of the OLED array. A shadow mask is a tool used to pattern a substrate; for example, in this embodiment, any suitable deposition method such as sputtering, thermal evaporation, and spin coating can be used in conjunction with a shadow mask to deposit the desired pattern of first color electrodes 14A, 14B on DBR 12.

[0153] 10D-10G show a series of photolithography steps for patterning the first optical filler layer. Photolithography is a widely used fabrication technique to transfer a pattern onto a substrate through a photomask using photoresist and ultraviolet (UV) light. The photomask can be, for example, a thin plate with a sub-micrometer or nanometer sized pattern with opaque and transparent areas of the desired pattern, preferably comprising glass or fused silica. The photomask is used in combination with UV light to transfer the pattern from the mask to the substrate in high resolution photolithography. Photolithography is a process that begins with cleaning the top surface with a solvent, such as acetone, methanol, and isopropanol, followed by deionized water. It should be noted that a shadow mask can be used for any patterning step in this embodiment if the desired pixel size is larger than in this embodiment.

[0154] FIG. 10D shows a cross-sectional view of the embodiment after deposition of photoresist 74. Deposition can be accomplished, for example, by spin-coating deposition. Photoresist 74 is deposited on a structure comprising substrate 10 and DBR 12 having first color electrodes 14A, 14B thereon stacked on DBR 12 connected to substrate 10 by vias 16A, 16B, respectively. The structure with photoresist 74 is soft baked at a temperature below about 110° C. to remove solvent content. A patterning step, for example using a photomask designed with a series of nano-sized opaque and transparent portions in a specific pattern, which can be transferred to the top layer during a photolithography process. The photomask can be composed of glass, fused silica, or other suitable material. In this embodiment, the photomask is applied with a design having opaque portions in the pattern of first color electrodes 14A, 14B.

[0155] In FIG. 10E, the structure on the substrate 10 with the photomask is exposed to UV light. The UV light causes a chemical change that allows the photoresist 74 to be removed by etching. During photolithography, the photoresist 74 in the areas where it is desired to apply the first optical filler layer between the first electrodes 14A, 14B is removed, exposing the DBR 12, while the photoresist above the first electrodes 14A, 14B with the vias 16A, 16B remains intact. There are two types of photoresist: positive and negative. Positive photoresist is chemically changed when exposed to UV light to become soluble to etching, and only the exposed portions of the photoresist are removed by etching after UV exposure. The unexposed portions of the photoresist remain insoluble. In negative photoresist, the portions of the photoresist exposed to light become insoluble to etching. In this example, the photoresist 74 is preferably a positive photoresist, which has been found to be easier to control during photolithography because it can maintain size and pattern, has better etch resistance, and has excellent resolution and thermal stability. However, it is understood that a negative photoresist may also be used. Etching removes the photoresist layer from the embodiment by chemical etching, which may be called a developer, plasma etching, reactive ion etching, and ion beam milling. The photoresist material and the etching process, which may include a developer material, are specifically designed to work together to create high quality patterns without affecting other deposited materials on the embodiment. The mask or photomask controls where the light (i.e., UV light for photolithography) is irradiated on the wafer or substrate. The photomask may comprise an opaque plate with perforations or transparent areas that allow the light to shine at predetermined locations. The photomask material may include, for example, fused silica (quartz glass) with a coating pattern made of chrome. The photomask may be further coated with Teflon to help prevent adsorption problems during contact photolithography.In the case of a positive photoresist, the photomask has the desired pattern that is transferred to the embodiment by a photolithography process.

[0156] FIG. 10F shows the deposition of the first optical filler layer 18 over the entire OLED array. The first optical filler layer 18 can be deposited, for example, by sputtering, thermal evaporation, chemical vapor deposition, or atomic layer deposition on the DBR 12 and the photoresist 74 protecting the first electrodes 14A, 14B and the vias 16A, 16B. One preferred method of deposition is sputtering, which allows the designer to precisely adjust the thickness of the layers during deposition. The substrate 10 and layers thereon are then exposed to a stripper that removes the photoresist 74 as well as the first optical filler layer 18 deposited on the photoresist 74. The photoresist stripper interacts with, fragments, and removes the photoresist 74 while leaving the remaining layers already deposited on the substrate intact. Some examples of photoresist strippers are solvents such as acetone, NMP (1-methyl-2-pyrrolidone), dimethylsulfoxide, alkaline media such as 2-3% concentrated potassium hydroxide (KOH) or sodium hydroxide (NaOH), hydrofluoroethers; commercial strippers such as AZ100, Techni Strip P1316, P1331, N1555, and combustion with O2 plasma.

[0157] 10G shows the substrate 10 after the remaining photoresist and the first optical filler layer 18 deposited on the photoresist have been removed. It should be noted that this entire photolithography process can be repeated for the deposition of all subsequent optical filler layers disclosed herein. The DBR 12, the first electrodes 14A, 14B, and the vias 16A, 16B remain intact on the substrate 10.

[0158] Figure 10H shows a top view of the embodiment of Figure 10G after photolithography steps have been completed, showing the pattern of first color electrodes 14A, 14B and first optical filler layer 18 across the OLED array, and in particular how the patterning eliminates spacing between the OLED devices.

[0159] FIG. 10I shows a second optical filler layer 20 deposited on the first optical filler layer 18, covering the entire first optical filler layer 18 and partially overlapping the first color electrodes 14A, 14B to form overlap regions 80A, 80B. The second optical filler layer 20 can be deposited, for example, by sputtering, thermal evaporation, chemical vapor deposition, or atomic layer deposition. One preferred method of deposition is sputtering, which allows the designer to precisely adjust the thickness of the layer during deposition. The overlap regions 80A, 80B provide a tolerance that mitigates alignment errors in manufacturing, thus increasing the aperture ratio of the display by reducing the lateral spacing between the OLED devices on the substrate 10. The DBR 12, the first electrodes 14A, 14B, and the first color vias 16A, 16B remain intact on the substrate 10.

[0160] 10J shows the second color via 24 dry etched using reactive ion etching through the first optical filler layer 18, the second optical filler layer 20, and the DBR 12. The first electrodes 14A, 14B and the first color vias 16A, 16B remain intact on the substrate 10.

[0161] 10K shows the second color electrode 22 deposited by sputtering on the second optical filler layer 20, with the width of the second color electrode 22 approximately equal to the width of the second optical filler layer 20. The second color via 24 provides electrical connection of the second color electrode 22 to the substrate 10. The first optical filler layer 18, the first color electrodes 14A, 14B, the first color vias 16A, 16B, and the DBR 12 remain intact on the substrate 10.

[0162] 10L shows a top view of the embodiment after the second color electrode 22 has been deposited. The patterning of the first color electrodes 14A, 14B and the second color electrode 22 allows for minimal spacing between the OLED devices on the OLED array. The emitted color can be any color on the visible light spectrum, including but not limited to red, yellow, blue, and green. A preferred combination for the two-color arrangement is yellow and blue emission.

[0163] Figure 10M shows a white OLED stack 26 deposited on a substrate 10 on which second color electrode 22, second optical filler layer 20, first optical filler layer 18, second color via 24, first color electrodes 14A, 14B, first color vias 16A, 16B, and DBR 12 have already been deposited. The white OLED stack 26 shown in Figure 10M comprises a series of organic material layers, and each layer of the white OLED stack 26 can be deposited by thermal evaporation, spin casting, or inkjet printing.

[0164] 10N shows the final step of the fabrication process with the deposition of a cathode 28, which forms an optical microcavity for each OLED device in the OLED array. The cathode 28 can be deposited by thermal evaporation and sputtering. In this embodiment, thermal evaporation is the preferred deposition method. The plurality of first and second color microcavities formed by the second color electrode 22, the second optical filler layer 20, the first optical filler layer 18, the second color vias 24, the first color electrodes 14A, 14B, the first color vias 16A, 16B, and the DBR 12 together with the white OLED stack 26 form an OLED array device on the substrate 10.

[0165] 11A-11V show a step-by-step process for fabricating a three-color OLED array according to the present disclosure.

[0166] FIG. 11A shows the first step in fabrication, where DBR 12 is deposited on substrate 10. In this embodiment, substrate 10 is a TFT substrate, which is the device that forms the base structure of this embodiment. It is understood that DBR 12, as shown in FIG. 11A, comprises alternating high and low index dielectric layers. Each layer of DBR 12 can be deposited by sputtering, thermal evaporation, chemical vapor deposition, and atomic layer deposition. The preferred deposition method for this embodiment is sputtering.

[0167] 11B shows first color vias 16A, 16B dry etched through DBR 12 to connect to substrate 10. Each via can be etched by reactive ion etching, anodic plasma etching, magnetically enhanced reactive ion etching, triode reactive ion etching, and transmission coupled plasma etching. In this embodiment, the preferred dry etching method is reactive ion etching.

[0168] 11C shows first color electrodes 14A, 14B deposited on the DBR 12. First color vias 16A, 16B provide electrical connection of the first color electrodes 14A, 14B to the substrate 10. The electrodes can be patterned by sputtering, thermal evaporation, and spin coating. In this embodiment, sputtering is the preferred deposition method.

[0169] 11D-11G show a sequence of photolithography steps for patterning a first optical filler layer. Photolithography is a widely used manufacturing technique, and it is understood that the steps as described in FIG. 10D-10G may be repeated for the deposition of all optical filler layers disclosed herein.

[0170] 11D shows a cross-sectional view of the embodiment after deposition of photoresist 74. Deposition can be accomplished by spin-coating deposition. Photoresist 74 is deposited on a structure comprising a substrate 10 and a DBR 12 having first color electrodes 14A, 14B thereon stacked on the DBR 12 connected to the substrate 10 by first color vias 16A, 16B, respectively. In this embodiment, a photomask is applied with a design having opaque portions in the pattern of the first color electrodes 14A, 14B.

[0171] In Figure 11E, the structure with the photomask is exposed to UV light, which causes a chemical change in the photoresist 74 adjacent to the first color electrodes 14A, 14B, making it soluble for etching. In this embodiment, the photoresist 74 is a positive photoresist. The first color electrodes 14A, 14B, the first color vias 16A, 16B, and the layer of DBR 12 deposited on the substrate 10 remain intact.

[0172] FIG. 11F shows the deposition of the first optical filler layer 18 over the entire OLED array. The first optical filler layer 18 can be deposited by sputtering, thermal evaporation, chemical vapor deposition, atomic layer deposition. The preferred deposition method is sputtering, which allows the designer to precisely adjust the thickness of the layer during deposition. The substrate is then exposed to a stripping process that removes the photoresist 74 and the first optical filler layer 18 above the photoresist 74. The stripper can be a commercially available product that breaks up and removes the photoresist 74 without damaging the first optical filler layer 18, the first color electrodes 14A, 14B, the first color vias 16A, 16B, and the layer of DBR 12 deposited on the substrate 10.

[0173] 11G shows the embodiment after removing the remaining photoresist and the first optical filler layer 18 deposited on the photoresist. The first optical filler layer 18, the first color electrodes 14A, 14B, the first color vias 16A, 16B, and the DBR 12 layers remain intact on the substrate 10.

[0174] 11H shows a top view of the embodiment after the photolithography steps are completed, showing the pattern of the first color electrodes 14A, 14B and first optical filler layer 18 across the OLED array, specifically how the patterning eliminates spacing between the OLED devices in the OLED array.

[0175] FIG. 11I shows the deposition of a second optical filler layer 20 partially on the first optical filler layer 18 and partially on the first color electrode 14A to form an overlap region 80A. The second optical filler layer 20 can be deposited by sputtering, thermal evaporation, chemical vapor deposition, atomic layer deposition. One preferred method of deposition is sputtering, which allows the designer to precisely adjust the thickness of the layer during deposition. The overlap region 80A provides a tolerance that mitigates alignment errors in manufacturing, thus increasing the aperture ratio of the display by reducing the lateral spacing between the OLED devices on the substrate 10. The first optical filler layer 18, the first color electrodes 14A, 14B, the first color vias 16A, 16B, and the DBR 12 layers remain intact on the substrate 10.

[0176] 11J shows second color vias 24 formed by dry etching using reactive ion etching through first optical filler layer 18, second optical filler layer 20, and DBR 12. The layers of first color electrodes 14A, 14B, first color vias 16A, 16B, and DBR 12 remain intact on substrate 10.

[0177] 11K shows the deposition, for example by sputtering, of a second color electrode 22 on the second optical filler layer 20, with the width of the second color electrode 22 approximately equal to the width of the second optical filler layer 20. A second color via 24 provides an electrical connection of the second color electrode 22 to the substrate 10. The first optical filler layer 18, the first color electrodes 14A, 14B, the first color vias 16A, 16B, and the DBR 12 layer remain intact on the substrate 10.

[0178] 11L shows a top view of the embodiment after deposition of second color electrode 22. The patterning of first color electrodes 14A, 14B, and second color electrode 22 and first optical filler layer 18, upon which the third electrode will eventually be deposited, allows for minimal spacing between OLED optical microcavity devices on the OLED array.

[0179] Figures 11M-11P show a sequence of photolithography steps for patterning the third optical filler layer. Photolithography is a widely used manufacturing technique, and it is understood that the steps as described in Figures 10D-10G may be repeated for the deposition of all optical filler layers disclosed herein.

[0180] FIG. 11M shows a cross-sectional view of the embodiment after deposition of photoresist 74. Deposition can be accomplished by spin-coating deposition. Photoresist 74 is deposited on a structure comprising a substrate 10 on which a DBR 12 is deposited, where first color electrodes 14A, 14B are stacked on the DBR 12 and connected to the substrate 10 by first color vias 16A, 16B, respectively, a first optical filler layer 18 is deposited on the DBR 12, a second optical filler layer 20 and a second color electrode 22 are stacked on the first optical filler layer 18, and the second color electrode 22 is connected to the substrate 10 by a second color via 24. A photomask is then designed with opaque portions in the pattern of the first color electrodes 14A, 14B and the second color electrode 22, partially covering the first color electrode 14B.

[0181] In Figure 11N, the structure with the photomask is exposed to UV light, which causes a chemical change in the photoresist 74, making it soluble for etching in the clear areas of the photomask. In this embodiment, the photoresist 74 is a positive photoresist. The first optical filler layer 18, the first color electrodes 14A, 14B, the first color vias 16A, 16B, the second optical filler layer 20, the second color electrodes 22, the second color vias 24, and the DBR 12 layers remain intact on the substrate 10.

[0182] FIG. 11O shows the deposition of the third optical filler layer 58 on top of the photoresist 74 that is deposited across the entire OLED array. The third optical filler layer 58 can be deposited by, for example, sputtering, thermal evaporation, chemical vapor deposition, or atomic layer deposition. One preferred method of deposition is sputtering, which allows the designer to precisely adjust the thickness of the layer during deposition. The substrate 10 is then exposed to a stripping process that removes the photoresist 74 and the third optical filler layer 58 deposited on the photoresist 74. The stripper can be a commercially available product that fragments and removes the photoresist 74 without damaging the other layers underneath. The first optical filler layer 18, the first color electrodes 14A, 14B, the first color vias 16A, 16B, the second optical filler layer 20, the second color electrodes 22, the second color vias 24, and the DBR 12 layers remain intact on the substrate 10.

[0183] 11P shows the substrate 10 and its deposited layers after removing the remaining photoresist and the third optical filler layer 58 deposited on the photoresist. The remaining third optical filler layer 58 may partially cover the first optical filler layer 18 and the first color electrode 14B to form an overlap region 80C. The first optical filler layer 18, the first color electrodes 14A, 14B, the first color vias 16A, 16B, the second optical filler layer 20, the second color electrode 22, the second color vias 24, and the DBR 12 layers remain intact on the substrate 10.

[0184] FIG. 11Q shows a fourth optical filler layer 60 deposited on the third optical filler layer 58, which may overlap the second color electrode 22 to form an overlap region 80D. The fourth optical filler layer 60 may be deposited, for example, by sputtering, thermal evaporation, chemical vapor deposition, or atomic layer deposition. One preferred method of deposition is sputtering, which allows the designer to precisely adjust the thickness of the layer during deposition. The overlap regions 80C, 80D may mitigate alignment errors in manufacturing, thus increasing the aperture ratio of the display by reducing the lateral spacing between the OLED devices on the substrate 10. The first optical filler layer 18, the first color electrodes 14A, 14B, the first color vias 16A, 16B, the second optical filler layer 20, the second color electrode 22, the second color vias 24, and the DBR 12 layers remain intact on the substrate 10.

[0185] 11R shows the third color via 64 dry etched using reactive ion etching through the first optical filler layer 18, the third optical filler layer 58, the fourth optical filler layer 60, and the DBR 12. The first optical filler layer 18, the first color electrodes 14A, 14B, the first color vias 16A, 16B, the second optical filler layer 20, the second color electrode 22, and the second color vias 24 remain intact on the substrate 10.

[0186] 11S shows a third color electrode 62 deposited, for example by sputtering, on the fourth optical filler layer 60. The width of the third color electrode 62 is approximately equal to the width of the fourth optical filler layer 60. A third color via 64 provides an electrical connection of the third color electrode 62 to the substrate 10. The first optical filler layer 18, the first color electrodes 14A, 14B, the first color vias 16A, 16B, the second optical filler layer 20, the second color electrode 22, the second color vias 24, the third optical filler layer 58, and the DBR 12 remain intact on the substrate 10.

[0187] 11T shows a top view after deposition of the third color electrode 62. The patterning of the first color electrodes 14A, 14B, second color electrode 22, and third color electrode 62 allows for minimal spacing between OLED devices on the OLED array. The emitted color can be any color on the visible light spectrum, including but not limited to red, yellow, blue, and green. A preferred combination of a three-color arrangement is red, green, and blue emission.

[0188] FIG. 11U shows a white OLED stack 26 deposited over the entire OLED array. It is understood that the white OLED stack 26 shown in FIG. 11U comprises a series of layers preferably composed of organic materials. Each layer of the white OLED stack 26 can be deposited by thermal evaporation, spin casting, and inkjet printing. In this embodiment, the preferred method is thermal evaporation. The first optical filler layer 18, the first color electrodes 14A, 14B, the first color vias 16A, 16B, the second optical filler layer 20, the second color electrode 22, the second color vias 24, the third optical filler layer 58, the third color electrode 62, the third color vias 64, the fourth optical filler layer 60, and the DBR 12 remain intact on the substrate 10 under the white OLED stack 26.

[0189] FIG. 11V shows the final step of the fabrication process, depositing a cathode 28 on the white OLED stack 26 to form the optical microcavities for each OLED device in the OLED array. The cathode 28 can be deposited by thermal evaporation and sputtering. In this embodiment, thermal evaporation is the preferred deposition method. The first optical filler layer 18, the first color electrodes 14A, 14B, the first color vias 16A, 16B, the second optical filler layer 20, the second color electrode 22, the second color vias 24, the third optical filler layer 58, the third color electrode 62, the third color vias 64, the fourth optical filler layer 60, and the DBR 12 remain intact on the substrate 10.

[0190] All publications, patents, and patent applications mentioned in this specification are indicative of the level of skill of those skilled in the art to which this invention pertains, and are hereby incorporated by reference. The reference to any prior art in this specification is not, and should not be construed as, an acknowledgment or any form of suggestion that such prior art forms part of the common general knowledge.

[0191] The invention thus described, it will be apparent that it may be modified in many ways. Such variations are not to be regarded as a departure from the scope of the invention, and all such modifications as would be apparent to one skilled in the art are intended to be included within the scope of the following claims.

Claims

1. A substrate, A distributed Bragg reflector (DBR) on the substrate, A first-color electrode on the DBR defining a first-color microcavity, the first-color electrode being connected to the substrate via a first via, A first optical filling material layer on the DBR adjacent to the first-color electrode on the DBR, A second optical filling material layer on the first optical filling material layer and partially overlapping with the first-color electrode in an overlapping region, A second-color electrode on the second optical filling material layer defining a second-color microcavity, the second-color electrode being connected to the substrate via a second via, A white organic light-emitting diode (OLED) stack on the first-color electrode and on the second-color electrode, An upper electrode on the white OLED stack, An organic light-emitting diode device comprising the above.

2. The device according to claim 1, wherein the second-color electrode partially overlaps with the first-color electrode.

3. The first-color microcavity has a first-color optical path length between the DBR and the upper electrode through the first-color electrode, and the second-color microcavity has a second-color optical path length between the DBR and the upper electrode through the second-color electrode. The device according to claim 1 or 2.

4. The first-color optical path length and the second-color optical path length are adjusted to provide desired first-color and second-color pixels respectively. The device according to claim 1 or 2.

5. The device according to claim 1 or 2, wherein the first optical filling material layer and the second optical filling material layer contain a transparent polymer.

6. The device according to claim 1 or 2, wherein the first optical filling material layer and the second optical filling material layer contain a transparent inorganic dielectric.

7. The device according to claim 1 or 2, further comprising a pixel defining layer insulating the first-color electrode from the second-color electrode.

8. The device according to claim 7, wherein the pixel defining layer contains one or more of an inorganic insulating dielectric and an organic material.

9. The device according to claim 1 or 2, wherein the substrate is a thin-film transistor (TFT) substrate.

10. The device according to claim 1 or 2, further comprising a second DBR on the upper electrode.

11. The device according to claim 1 or 2, wherein the upper electrode is a cathode and the lower electrode is an anode.

12. The device according to claim 1 or 2, wherein the upper electrode is an anode and the lower electrode is a cathode.

13. On the electrode of the second color and below the white OLED laminate, a third optical filling material layer on the first optical filling material layer defining a microcavity of a third color; a fourth optical filling material layer on the third optical filling material layer and partially overlapping the electrode of the second color; on the fourth optical filling material layer, a third-color electrode that partially overlaps the second-color electrode and is connected to the substrate through a third via; The device according to claim 1 or 2, further comprising:

14. In a method for manufacturing a multicolor microcavity organic light-emitting diode (OLED) array, depositing a distributed Bragg reflector (DBR) on a substrate; depositing a first-color electrode defining a microcavity of a first color on the DBR, wherein the first-color electrode is connected to the substrate through a first via; depositing a first optical filling material layer adjacent to the first-color electrode on the DBR on the DBR; depositing a second optical filling material layer partially overlapping the first-color electrode in an overlapping region on the first optical filling material layer; depositing a second-color electrode defining a microcavity of a second color on the second optical filling material layer, wherein the second-color electrode is connected to the substrate through a second via; depositing a white organic light-emitting diode (OLED) laminate on the first-color electrode and on the second-color electrode; depositing an upper electrode on the white OLED laminate; A method comprising:

15. The method according to claim 14, wherein the white OLED laminate is deposited over the entire OLED array.

16. The method according to claim 14 or 15, wherein the white OLED laminate is deposited using thermal evaporation, spin casting, or inkjet printing.

17. The method according to claim 14 or 15, wherein the upper electrode is deposited using thermal evaporation or sputtering.

18. The method according to claim 14 or 15, further comprising depositing a pixel defining layer that insulates the first-color electrode from the second-color electrode.

19. The method according to claim 18, wherein the pixel defining layer is deposited using sputtering, spin coating, thermal evaporation, chemical vapor deposition, atomic layer deposition, or spin casting.

20. The method according to claim 14 or 15, further comprising depositing a second DBR on the upper electrode.

21. The method according to claim 14 or 15, wherein the electrode of the first color, the electrode of the second color, and the upper electrode are deposited using sputtering, thermal evaporation, or spin coating.

22. The method according to claim 14 or 15, wherein the first optical filling layer and the second optical filling layer are deposited using sputtering, thermal evaporation, chemical vapor deposition, or atomic layer deposition.

23. The method according to claim 14 or 15, wherein the DBR is deposited using sputtering, thermal evaporation, chemical vapor deposition, or atomic layer deposition.

24. Before depositing the white OLED laminate, depositing a third optical filling layer selected for a third color on the first optical filling layer, wherein the third optical filling layer overlaps with the electrode of the first color; depositing a fourth optical filling layer selected for the third color on the third optical filling layer, wherein the fourth optical filling layer overlaps with the electrode of the second color; depositing a series of electrodes of the third color on the fourth optical filling layer; The method according to claim 14 or 15, further comprising the above steps.

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